feat: gallery + generic blueprint viewer, add Grid blueprint

Refactor the List-specific screen into a data-driven, reusable viewer:
- generic Blueprint type + shared LoadState machine + registry
- vue-router: / (gallery) and /b/:slug (illustration)
- BlueprintViewer renders any blueprint; specimens stay bespoke
- add Grid blueprint (6 functions incl. Position) + GridSpecimen

DESIGN.md

@@ -0,0 +1,70 @@
+# Design — `blueprints`
+
+Decisions for building `blueprints` out from a single List illustration into a
+gallery of many. Terminology: see [CONTEXT.md](CONTEXT.md).
+
+## D1 · Content sourcing: hand-authored typed data + bespoke specimen
+
+Each blueprint is a **typed TS data module** (`src/data/<name>Blueprint.ts`),
+transcribed by hand from its ontology README, paired with a **bespoke Specimen**
+component. The generic **Viewer** renders everything else (Readout, composition map,
+state machine) from that data.
+
+- **Why not parse the ontology at build time?** The Specimen must be hand-built for
+  every blueprint regardless (the ontology only provides an ASCII sketch), so parsing
+  would automate only the cheap, structured text — at the cost of fragile
+  markdown/mermaid parsing and a build-time coupling to the ontology repo's exact
+  format. Not worth it.
+- **Source of truth** stays the `blueprint-ontology` repo; the data modules are a
+  faithful transcription, cited in each module's header.
+
+Structural split this implies:
+
+| Part                               | Generic (data-driven)                | Bespoke (per blueprint)             |
+| ---------------------------------- | ------------------------------------ | ----------------------------------- |
+| Chrome (title block, tabs, legend) | ✓                                    |                                     |
+| Readout (dossier per function)     | ✓                                    |                                     |
+| Composition map                    | ✓ (from `extends` + `composes` data) |                                     |
+| State machine                      | ✓ (from nodes/edges data)            |                                     |
+| Specimen                           |                                      | ✓ component slotted into the Viewer |
+
+## D2 · Routing: vue-router, URL per blueprint
+
+Add `vue-router`. Routes: `/` → Gallery, `/b/:slug` → the blueprint's illustration
+(e.g. `/b/list`). Deep-linkable and shareable; browser back/forward works. The nginx
+SPA fallback (`try_files … /index.html`) already serves client routes, so no server
+change is needed. A blueprint registry (`src/data/blueprints.ts`) maps `slug →
+{ data module, specimen component, meta }` and is the single source both the router
+and the Gallery read from.
+
+## D3 · Gallery: illustrated-only, grows over time
+
+The Gallery lists **only** blueprints that have an illustration; it grows as we add
+them. No greyed "planned" cards. Rationale: keeps the landing clean and truthful, and
+avoids maintaining metadata for 45 not-yet-built entries. A blueprint appears in the
+Gallery precisely when it is registered in `src/data/blueprints.ts`.
+
+## D4 · Build-out slice #1: foundation + Grid
+
+**Foundation (refactor, no UX change to List):**
+
+- `pnpm add vue-router`; `App.vue` → thin shell with a header (link home) + `<RouterView/>`.
+- `src/views/GalleryView.vue` (`/`) — cards from the registry.
+- `src/views/BlueprintView.vue` (`/b/:slug`) — resolves the registry entry, renders the Viewer.
+- `src/components/BlueprintViewer.vue` — the **generic Viewer**, generalized from the
+  current List-specific `App.vue`: title block, legend, function tabs + full view,
+  two panes, optional composition map + state machine, footer. Props: a `Blueprint`
+  object + the blueprint's Specimen component (injected via `<component :is>`).
+- Generic `Blueprint` type in `src/data/blueprint.ts` (signature, functions,
+  coreInvariants, optional composition, optional stateMachine, meta). `listBlueprint.ts`
+  conforms to it. Specimens move to `src/specimens/`.
+- `src/data/blueprints.ts` — registry: `slug → { meta, blueprint, specimen }`.
+
+**Content:** `gridBlueprint.ts` + `src/specimens/GridSpecimen.vue` (2D tile grid).
+
+**Ships:** Gallery listing List + Grid; `/b/list` (same UX, refactored) and `/b/grid`.
+
+**Gates before push:** `pnpm build` clean · `pnpm lint` · `pnpm fmt`; then commit → push
+(auto-deploys) → verify `https://blueprints.apoena.dev`.
+
+Subsequent slices add one blueprint each (Table, Feed, …).