feat: WordPress plugin versioning + heatmap fix + dynamic latest download

- Add VERSION file (1.5.4) for tracking WP plugin version
- Update plugin headers to 1.5.4 (cannaiq-menus.php, crawlsy-menus.php)
- Add dynamic /downloads/cannaiq-menus-latest.zip route that auto-redirects
  to highest version (no manual symlinks needed)
- Update frontend download links to use -latest.zip
- Fix StateHeatmap.tsx to parse API values as numbers (fixes string concat bug)
- Document versioning rules in CLAUDE.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CLAUDE.md

@@ -1195,3 +1195,32 @@ Every analytics v2 endpoint must:
 ---
 
 # END Analytics V2 spec extension
+
+---
+
+## WordPress Plugin Versioning
+
+The WordPress plugin version is tracked in `wordpress-plugin/VERSION`.
+
+**Current version:** Check `wordpress-plugin/VERSION` for the latest version.
+
+**Versioning rules:**
+- **Minor bumps (x.x.N)**: Bug fixes, small improvements - default for most changes
+- **Middle bumps (x.N.0)**: New features, significant improvements
+- **Major bumps (N.0.0)**: Breaking changes, major rewrites - only when user explicitly requests
+
+**When making WP plugin changes:**
+1. Read `wordpress-plugin/VERSION` to get current version
+2. Bump the version number (minor by default)
+3. Update both files:
+   - `wordpress-plugin/VERSION`
+   - Plugin header `Version:` in `cannaiq-menus.php` and/or `crawlsy-menus.php`
+   - The `define('..._VERSION', '...')` constant in each plugin file
+
+**Plugin files:**
+| File | Brand | API URL |
+|------|-------|---------|
+| `cannaiq-menus.php` | CannaIQ | `https://cannaiq.co/api/v1` |
+| `crawlsy-menus.php` | Crawlsy (legacy) | `https://cannaiq.co/api/v1` |
+
+Both plugins use the same API endpoint. The Crawlsy version exists for backward compatibility with existing installations.