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/overview.html

@@ -3,10 +3,20 @@
 
 {% block title %}Overview — IETF Draft Analyzer{% endblock %}
 
+{% block extra_head %}<script src="/static/js/plotly.min.js"></script>{% endblock %}
+
 {% block content %}
-<div class="mb-8">
-    <h1 class="text-2xl font-bold text-white">Dashboard Overview</h1>
-    <p class="text-slate-400 text-sm mt-1">IETF AI/Agent Internet-Drafts at a glance</p>
+<div class="mb-8 flex flex-wrap items-start justify-between gap-4">
+    <div>
+        <h1 class="text-2xl font-bold text-white">Dashboard Overview</h1>
+        <p class="text-slate-400 text-sm mt-1">IETF AI/Agent Internet-Drafts at a glance. Drafts are fetched from the IETF Datatracker, then analyzed by Claude AI across five dimensions (novelty, maturity, overlap, momentum, relevance) to produce a composite score from 1.0 to 5.0.</p>
+    </div>
+    <a href="/export/obsidian"
+       class="inline-flex items-center gap-2 px-4 py-2 bg-purple-600/80 hover:bg-purple-500 text-white text-sm font-medium rounded-lg transition-colors flex-shrink-0"
+       title="Download all research data as an Obsidian vault with interlinked notes, Mermaid charts, and YAML frontmatter">
+        <svg class="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M12 10v6m0 0l-3-3m3 3l3-3m2 8H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z"/></svg>
+        Download for Obsidian
+    </a>
 </div>
 
 <!-- Stat cards -->
@@ -41,11 +51,13 @@
 <!-- Charts row 1: Score distribution + Category donut -->
 <div class="grid grid-cols-1 lg:grid-cols-2 gap-6 mb-6">
     <div class="bg-slate-900 rounded-xl border border-slate-800 p-5">
-        <h2 class="text-sm font-semibold text-slate-300 mb-3">Composite Score Distribution</h2>
+        <h2 class="text-sm font-semibold text-slate-300 mb-1">Composite Score Distribution</h2>
+        <p class="text-xs text-slate-500 mb-3">Weighted average of five AI-rated dimensions (novelty 20%, maturity 20%, uniqueness 20%, momentum 20%, relevance 20%). Higher scores indicate drafts that are novel, mature, unique, gaining traction, and highly relevant to AI agent infrastructure.</p>
         <div id="scoreHist" style="height: 300px;"></div>
     </div>
     <div class="bg-slate-900 rounded-xl border border-slate-800 p-5">
-        <h2 class="text-sm font-semibold text-slate-300 mb-3">Drafts by Category</h2>
+        <h2 class="text-sm font-semibold text-slate-300 mb-1">Drafts by Category</h2>
+        <p class="text-xs text-slate-500 mb-3">Categories are assigned by Claude during analysis. A draft can belong to multiple categories (e.g., both "A2A protocols" and "AI safety/alignment").</p>
         <div id="categoryPie" style="height: 300px;"></div>
     </div>
 </div>