feat: v3.4.0 — OpenPanel plugin public release (42 tools)

OpenPanel product analytics plugin fully reviewed, tested, and published.
Works with both self-hosted and cloud (openpanel.dev) instances.

- 42 tools: event tracking, data export, analytics, project/client management
- All tools use public REST APIs (Track, Export, Insights, Manage)
- Client modes: write (tracking), read (analytics), root (full access)
- Service page with description, setup notes, WordPress plugin download
- Dynamic URL hints in Add Site form
- 62 unit tests
- ENABLED_PLUGINS default now includes openpanel

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/plugin_visibility.py

@@ -15,7 +15,7 @@ Usage:
 import os
 
 # Default plugins available to public (OAuth) users
-DEFAULT_PUBLIC_PLUGINS = {"wordpress", "woocommerce", "supabase"}
+DEFAULT_PUBLIC_PLUGINS = {"wordpress", "woocommerce", "supabase", "openpanel"}
 
 
 def _parse_plugins(val: str) -> set[str]: