Fix remaining critical, high, and medium issues from 4-perspective review

Critical fixes:
- Fix rating clamp range 1-10 → 1-5 (actual scale)
- Add `ietf ideas convergence` command (SequenceMatcher at 0.75 threshold)
- Fix "628 cross-org ideas" → 130 (verified from current DB) across 8 files

Security fixes:
- Sanitize FTS5 query input (strip special chars + boolean operators)
- Add rate limiting (10 req/min/IP) on Claude-calling endpoints
- Change <path:name> → <string:name> on draft routes

Codebase fixes:
- Add Database context manager (__enter__/__exit__)
- Wire false_positive filtering into queries (exclude by default in web UI)
- Fix Post 3 arithmetic ("~300" → "~409" distinct proposals)

Content & licensing:
- Add MIT LICENSE file
- Add IPR/FRAND notes (BCP 79, RFC 8179) to Posts 03 and 07
- Qualify "4:1 safety ratio" with monthly variation in 6 remaining files
- Add "Data as of March 2026" freeze-date headers to all 10 blog posts
- Hedge causal language in Post 04

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/webui/templates/gaps.html

@@ -6,7 +6,7 @@
 {% block content %}
 <div class="mb-6">
     <h1 class="text-2xl font-bold text-white">Gap Explorer</h1>
-    <p class="text-slate-400 text-sm mt-1">{{ gaps | length }} identified gaps in AI/agent standards coverage — click any gap to explore details or generate a draft</p>
+    <p class="text-slate-400 text-sm mt-1">{{ gaps | length }} identified gaps in AI/agent standards coverage. Gaps are identified by Claude AI analyzing the full corpus of drafts to find areas where important problems lack adequate proposals. Severity reflects urgency: <span class="text-red-400">critical</span> = blocking issue with no draft addressing it, <span class="text-orange-400">high</span> = partially addressed but incomplete, <span class="text-yellow-400">medium</span> = some coverage exists but more work needed, <span class="text-green-400">low</span> = minor gap or niche concern.</p>
 </div>
 
 <!-- Action bar -->