feat(assets): add static assets service for RefRef scripts (#40)

* feat(assets): add static assets service for RefRef scripts

- Introduced a new `assets` application to serve static scripts for attribution tracking and referral widgets via Cloudflare.
- Implemented build scripts to copy and prepare assets for deployment, including versioning and checksum generation.
- Configured CORS and caching headers for optimal performance in production.
- Added comprehensive README documentation for setup, deployment, and usage instructions.
- Updated environment variables in the webapp to point to the new assets service.
- Created necessary configuration files for TypeScript, Wrangler, and Git ignore settings.
- Enhanced the overall project structure to support the new assets service.

* feat(assets): migrate to Cloudflare Workers Static Assets architecture

- Updated the assets service to utilize the new Cloudflare Workers Static Assets platform, replacing the previous Pages setup.
- Introduced a Worker script (`src/index.ts`) for handling routing, caching, and CORS headers.
- Replaced `wrangler.jsonc` with `wrangler.toml` for configuration, aligning with the new architecture.
- Removed obsolete `_headers` and `_redirects` files, now managed by the Worker.
- Enhanced TypeScript support and added necessary dependencies for the new setup.
- Updated README and migration documentation to reflect changes and provide guidance for deployment and local testing.

Author: nchopra

apps/assets/.gitignore

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+# Build outputs
+dist/
+
+# Generated assets (built from packages)
+public/*.js
+public/*.js.map
+
+# Keep configuration files
+!public/_headers
+!public/_redirects
+
+# Dependencies
+node_modules/
+
+# TypeScript
+*.tsbuildinfo
+
+# Environment
+.env
+.env.local
+.env.*.local

apps/assets/MIGRATION.md

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+# Migration to Cloudflare Workers Static Assets
+
+## What Changed
+
+Cloudflare has unified Workers and Pages into a single **Workers Static Assets** platform. Our implementation has been updated to use this new architecture.
+
+## Old vs New Architecture
+
+### Before (Incorrect)
+```
+❌ Used wrangler.jsonc (wrong format)
+❌ Had main = "." (invalid)
+❌ Used _headers and _redirects files (Pages-only features)
+❌ No Worker script
+❌ Relied on Pages behavior for routing
+```
+
+### After (Correct)
+```
+✅ Uses wrangler.toml (correct format)
+✅ Has main = "src/index.ts" (Worker script)
+✅ Worker handles all routing and headers
+✅ Uses env.ASSETS binding to fetch static files
+✅ Follows Workers Static Assets best practices
+```
+
+## Key Changes
+
+### 1. Added Worker Script (`src/index.ts`)
+
+The Worker script handles:
+- **Route mappings**: `/scripts/widget.js` → `/widget.v1.js`
+- **Aliases**: `/attribution.latest.js` → `/attribution.v1.js`
+- **Cache headers**: Immutable for versioned, short cache for aliases
+- **CORS**: Automatic CORS headers for all scripts
+
+### 2. Updated Configuration (`wrangler.toml`)
+
+```toml
+# Before
+main = "."                    # ❌ Invalid
+
+# After
+main = "src/index.ts"         # ✅ Points to Worker script
+
+[assets]
+directory = "./public"
+binding = "ASSETS"            # ✅ Required for env.ASSETS.fetch()
+```
+
+### 3. Removed Obsolete Files
+
+- ❌ Deleted `_headers` (now handled in Worker)
+- ❌ Deleted `_redirects` (now handled in Worker)
+- ❌ Removed `wrangler.jsonc` (renamed to `.toml`)
+
+### 4. Added TypeScript Support
+
+```json
+{
+  "types": ["@cloudflare/workers-types"]
+}
+```
+
+## How It Works Now
+
+### Request Flow
+
+1. Request arrives: `https://assets.refref.ai/scripts/attribution.js`
+2. Worker checks route map: Maps to `/attribution.v1.js`
+3. Worker fetches from storage: `env.ASSETS.fetch(request)`
+4. Worker adds headers:
+   - `Cache-Control: public, max-age=3600`
+   - `Access-Control-Allow-Origin: *`
+5. Response sent to client
+
+### Supported URLs
+
+All these work automatically:
+
+```
+✅ /attribution.v1.js          (direct, immutable)
+✅ /widget.v1.js                (direct, immutable)
+✅ /attribution.latest.js       (alias to v1)
+✅ /widget.latest.js            (alias to v1)
+✅ /attribution.js              (alias to v1)
+✅ /widget.js                   (alias to v1)
+✅ /scripts/attribution.js      (backward compatibility)
+✅ /scripts/widget.js           (backward compatibility)
+```
+
+## Benefits of New Architecture
+
+1. **Unified Platform**: No more confusion between Workers and Pages
+2. **Code-based Routing**: Explicit, testable routing logic
+3. **Dynamic Control**: Can add logic, A/B testing, feature flags, etc.
+4. **Better Performance**: Cloudflare's asset storage + Worker caching
+5. **Type Safety**: Full TypeScript support with Workers types
+
+## Deployment
+
+No changes to deployment commands:
+
+```bash
+# Production
+pnpm -F @refref/assets deploy:cloudflare
+
+# Dev/Preview
+pnpm -F @refref/assets deploy:cloudflare:dev
+```
+
+The Worker + assets are deployed together as a single unit.
+
+## Testing Locally
+
+```bash
+# Start local dev server
+pnpm -F @refref/assets preview
+
+# Test routes
+curl http://localhost:8787/attribution.v1.js
+curl http://localhost:8787/scripts/widget.js
+```
+
+## Migration Checklist
+
+- [x] Created Worker script (`src/index.ts`)
+- [x] Updated `wrangler.toml` configuration
+- [x] Removed `_headers` and `_redirects` files
+- [x] Added `@cloudflare/workers-types` dependency
+- [x] Updated TypeScript configuration
+- [x] Updated README documentation
+- [x] Tested build process
+- [x] Ready for deployment
+
+## References
+
+- [Cloudflare Workers Static Assets Docs](https://developers.cloudflare.com/workers/static-assets/)
+- [Wrangler Configuration](https://developers.cloudflare.com/workers/wrangler/configuration/)
+- [Assets Binding](https://developers.cloudflare.com/workers/static-assets/binding/)