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/ask.html

@@ -102,6 +102,7 @@
             <div class="text-slate-300 text-sm leading-relaxed whitespace-pre-line">{{ result.answer }}</div>
         </div>
     {% else %}
+        {% if is_admin %}
         <!-- Synthesize button (costs tokens, result is cached permanently) -->
         <div class="answer-card rounded-xl border border-slate-800 p-5 mb-6">
             <div class="flex items-center justify-between">
@@ -118,6 +119,7 @@
                 </button>
             </div>
         </div>
+        {% endif %}
     {% endif %}
     </div>