Store category prompts as EXACT split legacy text, no boilerplate

The per-category prompt editor showed English machine boilerplate
("Role: description. Build JSON …", schema intro, {{var}} context lines)
because seed/sync baked the render framing into categories.prompt. Now the
stored overlay is exactly the legacy wp_product_categories.sql content,
split into the three sections a user would type themselves:

  --- Title ---        Slovenian naming formula
  --- Description ---  legacy <H2>/<p>/<ul> body structure
  --- Meta ---         legacy metaDescription instruction

Schema, role framing, and Name/Description/Category/Attrs product context
stay render-time only (system template + ensureCategoryEnhanceUserContext),
where they already existed.

- SplitLegacyCombinedEnhancePrompt: non-legacy input now returns "" —
  categories without seed/legacy content get their override CLEARED
  (company default) instead of being stuffed with the canonical template
  (e.g. parent categories like "Bela tehnika" absent from the SQL).
- CategoryEnhancePromptNeedsRepair flags stored boilerplate ("parsed as
  JSON", "Build JSON", retired Attributes section) so Sync rewrites old
  data to the clean shape; repair supports clearing (prompt = '{}').
- seed-a1 apply-category-prompts skips instead of writing template text.
- Web editor compose stores only the user's section text: empty sections
  keep bare markers, default bodies and the default preamble are never
  persisted (DEFAULT_SECTION_BODIES removed).
- Verified locally: apply rewrote 238 A1+Demo categories (216 exact
  splits, 22 cleared), zero boilerplate matches in DB, idempotent re-run
  (would_update=0).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/api/internal/catalog/fix_catalog_test.go

@@ -15,13 +15,15 @@ func TestCategoryEnhanceTemplateHasAttrs(t *testing.T) {
 		t.Fatalf("template missing {{attrs}}: %q", tpl)
 	}
 	if !aiprompts.CategoryEnhanceHasRoleSections(tpl) {
-		t.Fatal("repaired template must include title/description/meta/attributes sections")
+		t.Fatal("built-in template must include title/description/meta sections")
 	}
 	if !aiprompts.CategoryEnhancePromptNeedsRepair("legacy HTML prompt without attrs") {
 		t.Fatal("expected legacy prompt to need repair")
 	}
-	if aiprompts.CategoryEnhancePromptNeedsRepair(tpl) {
-		t.Fatal("canonical template should not need repair")
+	// The built-in template is render-time only; STORED copies of it are
+	// boilerplate pollution and must be repaired (cleared).
+	if !aiprompts.CategoryEnhancePromptNeedsRepair(tpl) {
+		t.Fatal("stored template text should need repair")
 	}
 }
 
@@ -32,21 +34,6 @@ func TestPlatformDemoNameConstant(t *testing.T) {
 	}
 }
 
-func TestRepairedCategoryEnhancePromptMapMatchesA1Demo(t *testing.T) {
-	t.Parallel()
-	want, err := repairedCategoryEnhancePromptMap()
-	if err != nil {
-		t.Fatal(err)
-	}
-	tpl := strings.TrimSpace(aiprompts.CategoryEnhanceUserTemplate)
-	if want["sl"] != tpl || want[company.LangPromptAny] != tpl {
-		t.Fatalf("want sl+* template, got %#v", want)
-	}
-	if !strings.Contains(tpl, "{{attrs}}") {
-		t.Fatal("template must include {{attrs}}")
-	}
-}
-
 func TestCategoryEnhancePromptMapOKAcceptsSplitOverlay(t *testing.T) {
 	t.Parallel()
 	legacy := `GPT predloga: