feat: add title and description fields to capture grammar

Implement | prefix for titles and // separator for descriptions
across the full stack: parser, schema, API, CLI, and web frontend.

- Parser: line-aware extraction for |title, |title // desc,
  // leading desc, body // inline desc. URL-safe (skips :// lines).
  Modifiers (#tag, @time, ^card) extracted from all segments.
- Schema: ALTER TABLE migration adds title, description columns
- DB: Entity/EntityUpdate structs, all CRUD queries updated
- API: title/description on create/update/response, body validation
  relaxed (title-only entries valid)
- CLI: shows title as scan label when present
- Web: parseInput mirrors Go parser, list shows title, detail pane
  renders title + description with double-click inline editing
- Tests: 10 new cases (grammar, entity, API) — 71 total, all pass

internal/db/entities_test.go

@@ -472,3 +472,99 @@ func TestAbsorb_SourceIsCard(t *testing.T) {
 		t.Error("source should be soft-deleted")
 	}
 }
+
+func TestCreate_WithTitleAndDescription(t *testing.T) {
+	s := testStore(t)
+	e := &Entity{
+		Body:        "body text",
+		Title:       ptr("nginx trick"),
+		Description: ptr("always forget this"),
+		Glyph:       GlyphNote,
+		Tags:        []string{"ops"},
+	}
+	if err := s.Create(e); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := s.Get(e.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got.Title == nil || *got.Title != "nginx trick" {
+		t.Errorf("title: got %v", got.Title)
+	}
+	if got.Description == nil || *got.Description != "always forget this" {
+		t.Errorf("description: got %v", got.Description)
+	}
+	if got.Body != "body text" {
+		t.Errorf("body: got %q", got.Body)
+	}
+}
+
+func TestCreate_WithoutTitle(t *testing.T) {
+	s := testStore(t)
+	e := &Entity{Body: "just body", Glyph: GlyphNote}
+	if err := s.Create(e); err != nil {
+		t.Fatal(err)
+	}
+
+	got, _ := s.Get(e.ID)
+	if got.Title != nil {
+		t.Errorf("expected nil title, got %v", got.Title)
+	}
+	if got.Description != nil {
+		t.Errorf("expected nil description, got %v", got.Description)
+	}
+}
+
+func TestUpdate_Title(t *testing.T) {
+	s := testStore(t)
+	e := &Entity{Body: "body", Glyph: GlyphNote}
+	s.Create(e)
+
+	newTitle := "new title"
+	if err := s.Update(e.ID, &EntityUpdate{Title: &newTitle}); err != nil {
+		t.Fatal(err)
+	}
+
+	got, _ := s.Get(e.ID)
+	if got.Title == nil || *got.Title != "new title" {
+		t.Errorf("title: got %v", got.Title)
+	}
+}
+
+func TestUpdate_Description(t *testing.T) {
+	s := testStore(t)
+	e := &Entity{Body: "body", Glyph: GlyphNote}
+	s.Create(e)
+
+	newDesc := "new desc"
+	if err := s.Update(e.ID, &EntityUpdate{Description: &newDesc}); err != nil {
+		t.Fatal(err)
+	}
+
+	got, _ := s.Get(e.ID)
+	if got.Description == nil || *got.Description != "new desc" {
+		t.Errorf("description: got %v", got.Description)
+	}
+}
+
+func TestAbsorb_PreservesTargetTitle(t *testing.T) {
+	s := testStore(t)
+	target := &Entity{Body: "target body", Title: ptr("target title"), Glyph: GlyphNote}
+	source := &Entity{Body: "source body", Title: ptr("source title"), Glyph: GlyphNote}
+	s.Create(target)
+	s.Create(source)
+
+	if err := s.Absorb(target.ID, source.ID); err != nil {
+		t.Fatal(err)
+	}
+
+	got, _ := s.Get(target.ID)
+	if got.Title == nil || *got.Title != "target title" {
+		t.Errorf("target title should be preserved, got %v", got.Title)
+	}
+	if got.Body != "target body\nsource body" {
+		t.Errorf("body: got %q", got.Body)
+	}
+}