feat: add knowledge stats, discourse sync, and tools to dashboard

[neuromechanist]

Summary

• Add discourse to sync types so Discourse sync status appears on dashboard
• Add KnowledgeStats model to /sync/status response with item counts per category (GitHub, papers, docstrings, discourse, FAQ, mailing list)
• Add available_tools_list to community public metrics endpoint
• Update dashboard frontend with knowledge base stats grid and available tools badges

Test plan

• uv run pytest tests/test_api/test_sync.py -v -- 18/18 passed
• uv run pytest tests/test_api/test_community.py -v -- passed
• uv run ruff check -- clean
• Verify on dev: curl "https://api.osc.earth/osa-dev/sync/status?community_id=mne" shows discourse in syncs and knowledge counts
• Verify on dev: curl "https://api.osc.earth/osa-dev/mne/metrics/public" shows available_tools_list
• Visit develop-demo.osc.earth and check knowledge stats and tools sections

Closes #239

[github-actions]

Dashboard Preview

Name	Link
Preview URL	https://feature-issue-239-dashboard-.osa-dash.pages.dev
Branch	feature/issue-239-dashboard-knowledge-stats
Commit	56d496b

This preview will be updated automatically when you push new commits.

[neuromechanist]

PR Review Summary

Reviewed by: code-reviewer, silent-failure-hunter, code-simplifier (run in parallel)

Critical Issues (2 found) -- FIXED

1. [silent-failure-hunter] "discourse" missing from trigger_sync() validation whitelist (sync.py:365). Status endpoint lists it as valid but trigger would reject it with 400.

   • Fix: Added "discourse" to valid_types tuple and docstring.

2. [code-reviewer + silent-failure-hunter] available_tools_list key absent from response when community_config is None (community.py:1378). Unlike config_health which always has a fallback, this key would silently disappear.

   • Fix: Added else branch with empty list fallback.

Important Issues (2 found) -- FIXED

3. [silent-failure-hunter] Tool derivation has no error handling (community.py:1378-1395). An AttributeError from a partially constructed config would crash the entire /metrics/public endpoint, losing all other data already computed.

   • Fix: Wrapped in try/except (AttributeError, TypeError) matching the adjacent config_health pattern.

4. [code-simplifier] Inline styles on tool badges and section headings bypass dark mode CSS (index.html). New elements had hardcoded light-mode colors.

   • Fix: Replaced with .section-heading and .tool-badge CSS classes; added dark mode rules for those plus .config-banner-warning and .config-banner-error.

Suggestions (2 found) -- FIXED

5. [code-simplifier] renderKnowledgeStats used repetitive push pattern for 6 categories.

   • Fix: Refactored to data-driven KNOWLEDGE_FIELDS array with .filter().map().

6. [code-simplifier] FAQ condition used inconsistent bool(config.mailman) wrapper.

   • Fix: Simplified to config.faq_generation and config.mailman.

Not addressed (out of scope, pre-existing)

• Broad except Exception in scheduler job retrieval (sync.py:307) -- pre-existing
• Path traversal hardening in find_logo_file -- pre-existing, IDs come from trusted registry
• X-Content-Type-Options: nosniff header for SVG responses -- pre-existing

Strengths

• escapeHtml() used consistently for all user-facing data (XSS prevention)
• Frontend gracefully handles missing/null data with guard clauses
• Exception handling uses specific types, not bare except
• KnowledgeStats model cleanly maps to existing get_stats() output
• Dark mode now fully supported for all new elements