- Add CommentService dependency to CommentsProvider
- Add createComment() method supporting both post and comment replies
- Store postCid alongside postUri for proper reply references
- Add input validation: 10k char limit using grapheme clusters
- Proper emoji counting (🎉 = 1 char, not 2)
- Wire up CommentService in main.dart

Reply reference logic:
- Reply to post: root=post, parent=post
- Reply to comment: root=post, parent=comment

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

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

- Create auth_interceptor.dart with reusable createAuthInterceptor()
- Handles 401 responses by refreshing token and retrying once
- Sign out user if refresh fails to prevent infinite loops
- Refactor VoteService to use shared interceptor
- CommentService already uses it (from previous commit)

Eliminates ~130 lines of duplicated interceptor code.

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

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

- Add CommentService with createComment() method that calls backend API
- Backend handles PDS writes via OAuth/DPoP (sealed token architecture)
- Add ValidationException to api_exceptions for client-side validation
- Add characters package for proper Unicode grapheme cluster counting

The comment creation flow:
Mobile → Coves Backend (sealed token) → User's PDS (DPoP)

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

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

- Update mock providers to remove VoteService dependency
- Add ViewerState to test fixtures for feed and comments
- Update FeedProvider tests for vote state initialization
- Update CommentsProvider tests for recursive vote state init
- Update VoteProvider tests for extractRkeyFromUri utility
- Remove obsolete vote service test methods (deleteVote, getUserVotes)
- Add generated mock files for auth service tests

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

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

main.dart:
- Remove voteService parameter from FeedProvider and CommentsProvider

CommentsProvider:
- Remove VoteService dependency - vote state from response viewer data
- Add _initializeCommentVoteState helper for recursive vote initialization
- On refresh: initialize all comments (server data is truth)
- On pagination: only initialize new comments (preserve optimistic state)

This completes the migration from VoteService.getUserVotes() to using
viewer state from API responses for both feed posts and comments.

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

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

- Remove VoteService dependency - vote state comes from feed response
- Replace getUserVotes + loadInitialVotes with per-post setInitialVoteState
- Use viewer.vote and viewer.voteUri from backend response
- Call setInitialVoteState for ALL posts to handle cross-device vote removal

This fixes the bug where votes would disappear on feed refresh:
1. Backend now populates viewer state from PDS cache
2. Feed provider initializes VoteProvider state from viewer data
3. Score adjustments are cleared to prevent double-counting

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

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

Vote Service:
- Remove deleteVote method - backend handles toggle logic
- Remove getUserVotes - vote state now comes from feed viewer data
- Remove unused ExistingVote and VoteInfo classes
- Handle empty uri/cid response as successful toggle-off
- Use shared extractRkeyFromUri utility

Vote Provider:
- Remove existingVoteRkey/Direction params from createVote call
- Remove loadInitialVotes - replaced by setInitialVoteState per-post
- Add extractRkeyFromUri static utility to VoteState
- Clear score adjustments in setInitialVoteState to prevent double-counting

This aligns with the backend's vote cache approach where viewer state
is populated from PDS on each request rather than relying on the
eventually-consistent AppView index.

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

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