Migrate comment record lexicon from social.coves.feed.comment to
social.coves.community.comment to align with community-focused
architecture.

Changes:
- Move lexicon from feed/comment.json to community/comment.json
- Update lexicon ID: social.coves.community.comment
- Update test data lexicons (3 files) to use new namespace

This is part of the broader namespace migration to organize all
community-related records under the community namespace.

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

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

Add two new scripts for generating realistic test data:

- generate_deep_thread.go: Creates deeply nested comment threads (100 levels)
for testing threading logic, depth limits, and performance

- generate_nba_comments.go: Generates NBA-themed comments with realistic
basketball discussion content for UX testing and demos

Both scripts:
- Insert directly into PostgreSQL (bypassing Jetstream for speed)
- Create realistic comment trees with varied content
- Useful for stress testing, performance validation, and demos

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

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

Remove deprecated 'version' field from docker-compose.dev.yml.
Docker Compose v2 ignores this field and it's no longer needed.

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

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

- Add source_name field to Perspective model for better attribution
- Extract source name from HTML anchor tags in parser
- Display source name in rich text (e.g., "The Straits Times" vs generic "Source")
- Improve spacing in highlights, perspectives, and sources lists (double newlines)
- Better visual separation between list items

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

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

Streamable and other providers return protocol-relative URLs (//cdn.example.com)
in their oEmbed thumbnail_url field. These fail when passed to the blob service
because http.NewRequest requires a full URL with scheme.

Fix:
- Add normalizeURL() helper to convert // → https://
- Apply to both oEmbed and OpenGraph thumbnail URLs
- Add comprehensive tests (6 test cases)

Example transformation:
//cdn-cf-east.streamable.com/image/abc.jpg
→ https://cdn-cf-east.streamable.com/image/abc.jpg

This ensures Streamable video thumbnails are properly downloaded and uploaded
as blobs, fixing missing thumbnails in video embeds.

Affects: All users posting Streamable/YouTube/Reddit links (not Kagi-specific)
Tested: Unit tests pass, build successful

Update Kagi News aggregator client for nested external embed structure,
add unfurling roadmap items, and include utility scripts for testing.

**Kagi News Aggregator Updates:**
- Update client to use nested "external" structure (social.coves.embed.external)
- Update tests for new embed format
- Update README with latest API requirements
- Fix E2E tests for lexicon schema changes

**PRD Backlog Additions:**
60 new lines documenting unfurling feature:
- URL metadata enrichment via oEmbed/OpenGraph
- Blob upload for thumbnails
- Cache strategy (24h TTL)
- Circuit breaker for provider failures
- Supported providers (Streamable, YouTube, Reddit, Kagi)

**.env.dev Updates:**
- Add unfurl service configuration
- Add blob upload settings
- Update PDS URLs for testing

**Development Scripts:**
- generate_test_comments.go: Generate test comment data
- post_streamable.py: Test Streamable unfurling E2E

**Summary:**
- Aggregator client: Updated for nested embed structure
- Documentation: Added unfurling feature to backlog
- Scripts: Testing utilities for development

All aggregator tests updated to match new lexicon schema.
Ready for deployment with backward-compatible migration path.

Add extensive test coverage for external embed thumb validation and blob
reference transformation in feed responses.

**Thumb Validation Tests** (post_thumb_validation_test.go):
7 test cases covering strict blob reference validation:
1. ❌ Reject thumb as URL string (must be blob ref)
2. ❌ Reject thumb missing $type field
3. ❌ Reject thumb missing ref field
4. ❌ Reject thumb missing mimeType field
5. ✅ Accept valid blob reference
6. ✅ Accept missing thumb (unfurl will handle)
7. Security: Prevents URL injection attacks via thumb field

**Feed Blob Transform Tests** (feed_test.go):
6 test cases for GetCommunityFeed blob URL transformation:
1. Transforms blob refs to PDS URLs
2. Preserves community PDSURL in PostView
3. Generates correct getBlob endpoint URLs
4. Handles posts without embeds
5. Handles posts without thumbs
6. End-to-end feed query validation

**Integration Test Updates:**
- Update post creation tests for content length validation
- Update post handler tests with proper context setup
- Update E2E tests for nested external embed structure
- Add helper for creating communities with PDS credentials
- Add createTestUser helper for unique test isolation

**Test Isolation:**
- Use unique DIDs per test (via t.Name() suffix)
- Prevent cross-test data contamination
- Proper cleanup with defer db.Close()

**Example Validation:**
```go
// ❌ This should fail validation:
"thumb": "https://example.com/thumb.jpg" // URL string

// ✅ This should pass validation:
"thumb": {
"$type": "blob",
"ref": {"$link": "bafyrei..."},
"mimeType": "image/jpeg",
"size": 52813
}
```

**Coverage:**
- Blob validation: 7 test cases
- Blob transformation: 6 test cases
- Feed integration: 99 added lines in feed_test.go
- Total: 13 new test scenarios

This ensures security (no URL injection), correctness (proper blob format),
and functionality (URLs work in API responses).