Add comprehensive Alpha launch readiness documentation and production
JWT verification testing infrastructure.

**Alpha Go-Live PRD** (docs/PRD_ALPHA_GO_LIVE.md):
- Track remaining work for alpha launch with real users
- P0 blockers: DPoP architecture fix, JWT verification (2 items)
- ✅ Validated handle resolution already implemented
- ✅ Validated comment_count reconciliation already implemented
- P1 infrastructure: Monitoring, logging, backups, load testing
- E2E testing recommendations (7 critical gaps identified)
- Timeline: 65-80 hours (~2-3 weeks)
- Go/no-go decision criteria and risk assessment

**JWT Verification Test** (tests/integration/jwt_verification_test.go):
- E2E test for JWT signature verification with real PDS
- Tests JWT parsing, JWKS fetching, and auth middleware
- Validates AUTH_SKIP_VERIFY=false production mode
- Handles both dev PDS (symmetric) and production PDS (JWKS)
- Tests tampered token rejection

Changes support alpha launch planning and production security validation.

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

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

Fixes two backlog issues:
1. Post comment_count reconciliation - Added tests proving it works
2. Handle resolution for block/unblock endpoints - Full implementation

Changes include:
- 15 new integration tests (all passing)
- Handle resolution with proper error handling (400/404/500)
- Updated documentation in PRD_BACKLOG.md
- Code formatting compliance with gofumpt

Auto-formatting comment blocks to comply with gofumpt standards.
No functional changes.

Mark the following backlog items as complete:
1. Post comment_count reconciliation (2025-11-16)
- Added comprehensive test coverage (4 test cases)
- Updated misleading FIXME comment to accurate documentation
- Verified existing reconciliation logic works correctly

2. Handle resolution for block endpoints (2025-11-16)
- Phase 3: Block/unblock endpoints now accept handles
- Added 11 test cases covering all identifier formats
- Proper error handling (400 for validation, 404 for not found)
- Phase 1 (post creation) was already complete

Both issues estimated at 2-3 hours each, completed with full test
coverage and documentation updates.

Update block and unblock handlers to accept at-identifiers (handles)
in addition to DIDs, resolving them via ResolveCommunityIdentifier().

Changes:
- Remove DID-only validation in HandleBlock and HandleUnblock
- Add ResolveCommunityIdentifier() call with proper error handling
- Map validation errors (malformed identifiers) to 400 Bad Request
- Map not-found errors to 404
- Map other errors to 500 Internal Server Error

Supported formats:
- DIDs: did:plc:xxx, did:web:xxx
- Canonical handles: gaming.community.coves.social
- @-prefixed handles: @gaming.community.coves.social
- Scoped format: !gaming@coves.social

Test coverage (11 test cases):
- Block with canonical handle
- Block with @-prefixed handle
- Block with scoped format
- Block with DID (backwards compatibility)
- Block with malformed identifiers (4 cases - returns 400)
- Block with invalid/nonexistent handle (returns 404)
- Unblock with handle
- Unblock with invalid handle

Addresses PR feedback: Validation errors now return 400 instead of 500

Fixes issue: Handle Resolution Missing
Affected: Post creation, blocking endpoints

Add comprehensive integration tests verifying that post comment_count
is correctly reconciled when comments arrive before their parent post
due to out-of-order Jetstream event delivery.

Test coverage:
- Single comment arrives before post - count reconciled to 1
- Multiple comments arrive before post - count reconciled correctly
- Mixed ordering (comments before and after post) - count accurate
- Idempotent post indexing preserves comment_count

Also update misleading FIXME comment in comment_consumer.go to accurate
NOTE explaining that reconciliation IS implemented in post_consumer.go
at lines 210-226.

Fixes issue: Post comment_count Never Reconciles
File: internal/atproto/jetstream/comment_consumer.go:362

Complete migration of comment namespace from social.coves.feed.comment
to social.coves.community.comment.

This migration aligns the comment system with the community-focused
architecture and ensures all comment records use the correct namespace.

Summary:
- ✅ Lexicon migrated to community/comment.json
- ✅ Database migration 018 applied successfully
- ✅ All backend code updated (consumer, service, validation)
- ✅ Server configuration updated for Jetstream
- ✅ All 22 integration tests passing
- ✅ Test scripts and data updated
- ✅ Documentation updated

Migration verified with:
- Unit tests: ✅ PASSING
- Integration tests: ✅ 22/22 PASSING
- Build: ✅ SUCCESS
- Database: ✅ Migration 018 applied

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

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