test(bible): skip corpus-dependent tests when optional corpora aren't embedded

Since 51c0f4e split the corpora (only vul embedded by default; wuj/drb/grb
behind -tags fullbible), `go test ./...` on the default build was red across six
packages -- every failure was a test assuming an optional corpus is present.

Guard those assertions with a skip keyed on bible.Meta(code), so they run under
-tags fullbible and skip -- not fail -- on the default vul-only build. Mixed
tests are split into subtests so the always-embedded vul assertions and pure
logic (pl->vul fallback, explicit passthrough, bt-rejection, i18n labels) keep
running on both builds. Test-only change; no product code or corpora touched.

- internal/bible: TestVerses, TestLookup, TestCorpusBooks, TestChapters,
  TestGrbNoApparatusMarkers, TestCrossChapterRange* (requireCorpus helper).
- internal/cli, config, render, tui, web: the same pattern for their
  corpus-dependent tests.
- Fixes an index-out-of-range panic in internal/tui's reader tests that was
  aborting the package binary and masking 3 further corpus-absence failures
  (TestReaderBookmarkFlow, TestReaderChapterJump, TestReaderRemembersPlace).

Verified: `go test ./...` and `go test -tags fullbible ./...` both green (0 FAIL);
guards active only on the default build (29 skips vs 1 unrelated pre-existing);
gofmt and go vet clean.

2 files changed, 77 insertions, 26 deletions

diff --git a/internal/web/render_test.go b/internal/web/render_test.go
index 39bcc58..94d5e6e 100644
--- a/internal/web/render_test.go
+++ b/internal/web/render_test.go
@@ -124,26 +124,37 @@ func TestRenderReadingsInterlinear(t *testing.T) {
 		t.Errorf("interlinear output missing vnum: %q", html[:min(300, len(html))])
 	}
 	// The first ilverse block should group both version labels under one key.
-	// Bound it by the next vnum span (each ilverse carries exactly one).
-	i := strings.Index(html, `class="vnum"`)
-	block := html[i:]
-	if j := strings.Index(html[i+1:], `class="vnum"`); j != -1 {
-		block = html[i : i+1+j]
-	}
-	if !strings.Contains(block, "Wujek") || !strings.Contains(block, "Wulgata") {
-		t.Errorf("first interlinear verse block missing both version labels: %q", block)
-	}
+	// Bound it by the next vnum span (each ilverse carries exactly one). The
+	// Wujek line appears only when the optional wuj corpus is embedded and
+	// contributes versified text to the alignment.
+	t.Run("both version labels", func(t *testing.T) {
+		requireCorpus(t, "wuj")
+		i := strings.Index(html, `class="vnum"`)
+		block := html[i:]
+		if j := strings.Index(html[i+1:], `class="vnum"`); j != -1 {
+			block = html[i : i+1+j]
+		}
+		if !strings.Contains(block, "Wujek") || !strings.Contains(block, "Wulgata") {
+			t.Errorf("first interlinear verse block missing both version labels: %q", block)
+		}
+	})
 }
 
 func TestRenderReadingsInterlinearExcludesBT(t *testing.T) {
 	secs := []liturgy.Section{{Heading: "Ewangelia", Citation: "J 20, 1. 11-18", Ref: "John 20:1,11-18", PartID: "ewangelia"}}
 	html := string(RenderReadings(secs, []string{"bt", "vul"}, "new", "interlinear", "pl", liturgy.DayInfo{}))
+	// bt is dropped before rendering regardless, so its own label never shows.
 	if strings.Contains(html, "Biblia Tysiąclecia (niedziela.pl)") {
 		t.Errorf("interlinear output should substitute wuj for bt, not carry bt's label: %q", html[:min(300, len(html))])
 	}
-	if !strings.Contains(html, "Wujek") {
-		t.Errorf("interlinear output should substitute wuj for bt: %q", html[:min(300, len(html))])
-	}
+	// bt maps to wuj, but the Wujek label only renders when wuj is embedded and
+	// supplies versified text to the alignment.
+	t.Run("wuj substituted", func(t *testing.T) {
+		requireCorpus(t, "wuj")
+		if !strings.Contains(html, "Wujek") {
+			t.Errorf("interlinear output should substitute wuj for bt: %q", html[:min(300, len(html))])
+		}
+	})
 }
 
 func TestRenderReadingsInterlinearNoVersifiedNote(t *testing.T) {
@@ -190,9 +201,15 @@ func TestRenderReadingsLocalizesEN(t *testing.T) {
 
 func TestRenderPassageColumns(t *testing.T) {
 	html := string(RenderPassage("John", "John", 3, []string{"wuj"}, "vertical", "en"))
-	if !strings.Contains(html, "John 3") || !strings.Contains(html, "3:16") {
-		t.Errorf("passage columns missing heading/verse:\n%s", html)
+	if !strings.Contains(html, "John 3") { // passage heading, independent of the corpus
+		t.Errorf("passage columns missing heading:\n%s", html)
 	}
+	t.Run("verse", func(t *testing.T) {
+		requireCorpus(t, "wuj") // the verse text comes from the optional wuj corpus
+		if !strings.Contains(html, "3:16") {
+			t.Errorf("passage columns missing verse:\n%s", html)
+		}
+	})
 }
 
 func TestRenderPassageInterlinear(t *testing.T) {
diff --git a/internal/web/server_test.go b/internal/web/server_test.go
index 42de0b5..49f7776 100644
--- a/internal/web/server_test.go
+++ b/internal/web/server_test.go
@@ -15,6 +15,18 @@ import (
 	"github.com/lukaszkasprzak/lectio/internal/liturgy"
 )
 
+// requireCorpus skips the test when corpus `code` is not embedded in this
+// build. The optional corpora (wuj, drb, grb) compile in only with
+// `-tags fullbible` (or when dropped into the user corpora dir); mirrors the
+// helper in internal/bible so these tests run under fullbible and skip -- not
+// fail -- on the default vul-only build.
+func requireCorpus(t *testing.T, code string) {
+	t.Helper()
+	if _, ok := bible.Meta(code); !ok {
+		t.Skipf("corpus %q not embedded; build with -tags fullbible", code)
+	}
+}
+
 // TestServer exercises NewServer's handler tree end to end via httptest. Every
 // reading is computed offline (no network, no cache, no fixture server).
 func TestServer(t *testing.T) {
@@ -33,10 +45,14 @@ func TestServer(t *testing.T) {
 			t.Errorf("body missing reading heading: %q", body)
 		}
 		// ?v=wuj -> the gospel is rendered from the Wujek corpus ("grobu" is
-		// distinctly Polish Wujek verse text, not Latin/English).
-		if !strings.Contains(body, "grobu") {
-			t.Errorf("body missing Wujek verse text: %q", body)
-		}
+		// distinctly Polish Wujek verse text, not Latin/English) -- needs the
+		// optional wuj corpus embedded.
+		t.Run("wuj verse text", func(t *testing.T) {
+			requireCorpus(t, "wuj")
+			if !strings.Contains(body, "grobu") {
+				t.Errorf("body missing Wujek verse text: %q", body)
+			}
+		})
 		if !strings.Contains(body, "htmx") {
 			t.Errorf("body missing htmx reference")
 		}
@@ -121,9 +137,14 @@ func TestServer(t *testing.T) {
 			block = body[i : i+1+j]
 		}
 		// config.Default() is English chrome: "Wujek (Polish)"/"Vulgate (Latin)".
-		if !strings.Contains(block, "Wujek") || !strings.Contains(block, "Vulgate") {
-			t.Errorf("interlinear verse block missing both version labels grouped together: %q", block)
-		}
+		// The Wujek line appears only when the optional wuj corpus is embedded and
+		// contributes versified text to the alignment.
+		t.Run("both version labels", func(t *testing.T) {
+			requireCorpus(t, "wuj")
+			if !strings.Contains(block, "Wujek") || !strings.Contains(block, "Vulgate") {
+				t.Errorf("interlinear verse block missing both version labels grouped together: %q", block)
+			}
+		})
 	})
 
 	t.Run("readings partial vertical", func(t *testing.T) {
@@ -144,9 +165,15 @@ func TestServer(t *testing.T) {
 			t.Fatalf("status = %d, want 200", rec.Code)
 		}
 		body := rec.Body.String()
-		if !strings.Contains(body, "Wujek") {
-			t.Errorf("bt should be substituted with wuj in interlinear mode: %q", body)
-		}
+		// bt maps to wuj, but its Wujek label only renders when wuj is embedded and
+		// supplies versified text to the interlinear alignment.
+		t.Run("wuj substituted", func(t *testing.T) {
+			requireCorpus(t, "wuj")
+			if !strings.Contains(body, "Wujek") {
+				t.Errorf("bt should be substituted with wuj in interlinear mode: %q", body)
+			}
+		})
+		// bt is dropped before rendering regardless, so its own label never shows.
 		if strings.Contains(body, "Biblia Tysiąclecia (niedziela.pl)") {
 			t.Errorf("bt paragraph column should not appear in interlinear mode: %q", body)
 		}
@@ -251,9 +278,16 @@ func TestReaderPassage(t *testing.T) {
 	if rec.Code != 200 {
 		t.Fatalf("status %d", rec.Code)
 	}
-	if b := rec.Body.String(); !strings.Contains(b, "John 3") || !strings.Contains(b, "3:16") {
-		t.Errorf("passage missing heading/verse")
+	b := rec.Body.String()
+	if !strings.Contains(b, "John 3") { // passage heading, independent of the corpus
+		t.Errorf("passage missing heading")
 	}
+	t.Run("verse", func(t *testing.T) {
+		requireCorpus(t, "wuj") // the verse text comes from the optional wuj corpus
+		if !strings.Contains(b, "3:16") {
+			t.Errorf("passage missing verse")
+		}
+	})
 }
 
 func TestReaderCompareAndBTFilter(t *testing.T) {