feat: add React frontend with search and mod pages

Add apps/web (Vite + React Router + Tailwind v4 + Zustand) with a search page and a mod page that analyzes saves via @tts/extract. Document the frontend in the README and docs.

docs/implementation-plan.md

@@ -21,20 +21,20 @@ Steam Workshop, fetching full TTS save files, and analyzing their contents.
 ## Non-goals (for now)
 
 - Backend traversal endpoints (deferred by design).
-- Frontend app (later; will consume `packages/extract` directly).
 - Caching / Redis / multi-instance concerns.
 
 ## Architecture
 
 ```
-apps/proxy ──► packages/tts ──► packages/shared
-      │            │
-      │            └──► (fetchMod → TTSMod)
-      ▼
-packages/extract ──► packages/tts (traverseMod) ──► packages/shared (types)
-   (isomorphic, used by future frontend)
+apps/web ──► apps/proxy ──► packages/tts ──► packages/shared
+      │            │            │
+      │            │            └──► (fetchMod → TTSMod)
+      │            ▼
+      └──► packages/extract ──► packages/shared (types)
+           (isomorphic, used by the frontend)
 ```
 
+- **`apps/web`** — React frontend (search + mod pages).
 - **`apps/proxy`** — Hono server. Search + fetch only. No traversal endpoints.
 - **`packages/tts`** — low-level fetcher: Steam API call, BSON parse, filename
   derivation. Returns raw parsed `TTSMod`.
@@ -54,16 +54,34 @@ tts-workshop/
 ├── docs/
 │   └── implementation-plan.md  # this file
 ├── apps/
-│   └── proxy/
+│   ├── proxy/
+│   │   ├── package.json
+│   │   ├── tsconfig.json
+│   │   └── src/
+│   │       ├── index.ts        # Hono app + @hono/node-server
+│   │       ├── routes/
+│   │       │   ├── search.ts   # GET /search?q=...&page=1
+│   │       │   ├── items.ts    # GET /items/:id, /items/:id/file
+│   │       │   └── health.ts   # GET /health
+│   │       └── env.ts          # zod env validation
+│   └── web/
 │       ├── package.json
 │       ├── tsconfig.json
+│       ├── vite.config.ts      # dev proxy → localhost:3000
+│       ├── index.html
 │       └── src/
-│           ├── index.ts        # Hono app + @hono/node-server
-│           ├── routes/
-│           │   ├── search.ts   # GET /search?q=...&page=1
-│           │   ├── items.ts    # GET /items/:id, /items/:id/file
-│           │   └── health.ts   # GET /health
-│           └── env.ts          # zod env validation
+│           ├── main.tsx        # React root + router
+│           ├── App.tsx         # layout + routes
+│           ├── api.ts          # fetch wrappers for /search, /items
+│           ├── index.css       # tailwind v4 entry
+│           ├── pages/
+│           │   ├── SearchPage.tsx
+│           │   └── ModPage.tsx
+│           ├── components/
+│           │   └── SearchResults.tsx
+│           └── stores/
+│               ├── searchStore.ts  # zustand
+│               └── modStore.ts     # zustand
 └── packages/
     ├── shared/
     │   └── src/
@@ -159,6 +177,27 @@ Hono server exposing search + fetch.
   - `GET /health` — liveness.
 - `env.ts` — zod validation of `STEAM_API_KEY`, `PORT`.
 
+### `apps/web`
+
+React frontend (Vite + React Router + Tailwind v4 + Zustand). Consumes the
+proxy API and `packages/extract` directly for analysis.
+
+- `main.tsx` — React root, `BrowserRouter`.
+- `App.tsx` — app shell (header) + routes: `/` (search), `/mod/:id` (mod).
+- `api.ts` — typed `fetch` wrappers for `/search` and `/items/:id`, plus a
+  `modFileUrl` helper for the raw-file download.
+- `pages/SearchPage.tsx` — search form, drives `searchStore`.
+- `pages/ModPage.tsx` — loads the mod via `modStore`, uses `@tts/extract`
+  (`flattenObjects`, `collectRefs`) to render objects and asset refs, and links
+  to the raw save file.
+- `components/SearchResults.tsx` — result grid + pagination.
+- `stores/searchStore.ts` / `stores/modStore.ts` — Zustand stores for search
+  and mod state.
+- `vite.config.ts` — dev proxy for `/search`, `/items`, `/health` →
+  `http://localhost:3000`.
+- Styling: Tailwind v4 via `@tailwindcss/vite`; `index.css` imports
+  `tailwindcss`.
+
 ## Endpoints
 
 | Method | Path                | Description                                  | Auth |
@@ -186,14 +225,16 @@ packages/extract    →  flatten objects / extract refs / download assets
 - `bson` — BSON deserialization.
 - `cheerio` — Workshop browse page scraping (backend only).
 - `zod` — validation.
+- `react`, `react-dom`, `react-router-dom`, `zustand` — frontend.
+- `vite`, `@vitejs/plugin-react`, `tailwindcss`, `@tailwindcss/vite` — frontend tooling.
 - `tsx`, `typescript`, `eslint`, `prettier` — tooling.
 
 ## Tooling
 
 - TypeScript strict mode.
-- `tsx` for dev, `tsc` for build.
+- `tsx` for dev, `tsc` for build; `vite` for the frontend dev server/build.
 - `vitest` for unit tests, colocated as `*.test.ts` next to sources.
-- Root scripts: `pnpm dev`, `pnpm build`, `pnpm test`, `pnpm lint`.
+- Root scripts: `pnpm dev`, `pnpm dev:web`, `pnpm build`, `pnpm test`, `pnpm lint`.
 
 ## Build order
 
@@ -203,7 +244,9 @@ packages/extract    →  flatten objects / extract refs / download assets
 3. `packages/tts` — fetch + parse (existing scraper code).
 4. `packages/extract` — objects, refs, download.
 5. `apps/proxy` — search + items + health routes, env validation.
-6. Wire up root scripts, `.env.example`, README.
+6. `apps/web` — React frontend (search + mod pages), consuming the proxy and
+   `packages/extract`.
+7. Wire up root scripts, `.env.example`, README.
 
 ## Risks / caveats