docs: replace SHOWCASE-ROADMAP.md with docs/backlog/ (17 WPs)

Turns the prior roadmap sketch into ordered, gated work packages (enforcement
gates, FP/DDD consistency, CIBG fidelity, Storybook curriculum, a11y) from the
2026-07-02 showcase-hardening audit.

docs/backlog/WP-13-cibg-gap-register.md

@@ -0,0 +1,79 @@
+# WP-13 — CIBG-gap register + hygiene + MDX
+
+Status: todo
+Phase: 2 — CIBG fidelity
+
+## Why
+
+User decision: hand-rolled token-bridge components are allowed **only if explicitly
+marked** as CIBG-gap extensions in code + Storybook, so every deviation from the design
+system is auditable. Plus two hygiene items from the audit: a dead wrapper to delete and
+the list-family rationale to document.
+
+## Read first
+
+- `docs/architecture/0003-*.md` (ADR-0003 — the token-bridge rationale this extends)
+- The audit's gap list (below)
+
+## Decisions (pre-made, don't relitigate)
+
+- Marker format (header comment in the component):
+  `// CIBG-GAP EXTENSION: <closest CIBG concept> — <why hand-rolled>` plus
+  `parameters: { cibgGap: true }` and a "CIBG-gap extension" line in the story
+  description.
+- **Keep all three list families** — each maps a distinct CIBG pattern: `task-list` →
+  Actieblok, `application-list` → Aanvragen, `choice-list` → Keuzelijst. Header comment
+  in each names its pattern. Consolidation would blur exactly the design-system mapping
+  this showcase demonstrates.
+- **Delete `upload-status-banner`** (`shared/ui/upload/upload-status-banner/`): a
+  23-line near-identity wrapper over `alert` with one consumer — inline `<app-alert>`
+  there.
+
+## Files
+
+Components to mark (closest CIBG concept in parens):
+- `skeleton`, `spinner` (Laadindicatie — no vendored class, verified)
+- `upload/` suite (Bestand-upload)
+- `rich-text-editor` (Tekstgebied)
+- `wizard-shell` (Wizard; error summary → Foutmelding, if WP-11 marked it)
+- `confirmation` (Bevestiging — verify: it wraps vendored classes; if so it needs no
+  marker, only the pattern comment)
+- `debug-state` (devtool, no CIBG concept)
+- `status-badge` (deliberate custom, documented in code), `card` (`.app-card`),
+  `placeholder-chip`
+Plus:
+- Delete `upload-status-banner` + its story; inline alert at its consumer
+- Header comments on `task-list`/`application-list`/`choice-list`
+- New `src/docs/cibg-gaps.mdx` — title `Foundations/CIBG Gap Register`
+- ADR-0003 gets a cross-link to the register
+
+## Steps
+
+1. Add the marker to each gap component + `cibgGap` story parameter.
+2. Delete the banner; migrate its one consumer; run its former story's states through
+   the consumer's story if coverage would drop.
+3. Write the MDX register: a table (component → closest CIBG concept → why) + the rule
+   "grep the vendored CSS before hand-rolling anything".
+4. Optional but cheap: a `check:cibg-gaps` script that greps markers and diffs against
+   the MDX table, so the register can't silently rot — add to `check:tokens`' CI step if
+   trivial, else note as skipped.
+
+## Acceptance criteria
+
+- [ ] Every component with hand-rolled surface CSS either wraps vendored classes or
+      carries the marker (spot-check with a grep for `styles: [` vs markers).
+- [ ] Register MDX complete, linked from ADR-0003.
+- [ ] `upload-status-banner` gone; consumer green; no story coverage lost.
+- [ ] List trio documented.
+
+## Verification
+
+GREEN + `npm run test-storybook:ci`.
+
+## Out of scope
+
+Rebuilding any gap component against the design system (they're sanctioned by decision).
+
+## Risks
+
+Low — mostly annotation; the deletion is the only behavior-touching change.