Merge main into prod

[Copilot]

Merges main into production. Key Pangea-specific changes since the last prod merge:

Course Joining & Knock Flow

• Client-side knock auto-accept via KnockTracker (account-data-persisted knocked room IDs, survives reinstall/logout)
• Auto-join knock-invite rooms on app launch via notification; custom invite reason drives background notification copy
• Push gateway URL read from environment config
• "Knock accepted" push notification body instead of generic "You have been invited"

Activity System

• Activities lazy-loaded per-topic instead of all-at-once on course details open
• Start Activity button disabled until a role is selected
• Redirect from Choose Role if session is already full
• Timer paused while activities load; feedback flag added to analytics activities
• Practice session ends on completion even if backup activities remain; progress value updated on complete

Analytics & Practice

• Unified use-type-aware practice scoring: suppresses wa words, prioritizes ga/ta words, per-activity-type recency
• Granular IGC/IT sub-types emitted instead of collapsed ga/ta
• Blocked constructs no longer counted as unused; language indicators added to DB entries

Phonetic Transcription v2

• Full PT v2 migration: flat pronunciations[] with per-pronunciation tts_phoneme, disambiguation by UD context, 24h disk cache

Language System

• Languages fetched directly from CMS REST API; hardcoded fallback retained for offline

TTS / STT

• STT transcription embedded in audio event content at send time
• POS + morph features forwarded on TTS requests for better pronunciation of heteronyms

Subscriptions

• Redundant pangea_user_id removed from payment link request
• Subscription management page launch unblocked; unsubscribed users see dedicated page in vocab practice

---

Thank you so much for your contribution to FluffyChat ❤️❤️❤️

• I have read and understood the contributing guidelines.

Pull Request has been tested on:

• Android
• iOS
• Browser (Chromium based)
• Browser (Firefox based)
• Browser (WebKit based)
• Desktop Linux
• Desktop Windows
• Desktop macOS

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.