Fix broken reference links and web UI bugs

- Fix RFC URLs with leading zeros (rfc0020 -> rfc20) via int filter
- Draft refs: internal link for drafts in our DB, Datatracker for external
- BCP refs: link to rfc-editor.org/info/bcpN
- Add DB connection teardown (@app.teardown_appcontext)
- Fix JS syntax error in gap_demo.html (HTML-escaped string in script tag)
- Add URL encoding to all query params in drafts.html and draft_detail.html
- Fix variable shadowing of Flask's g import in gaps_demo()
- Add None safety for ideas search data attribute

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

src/webui/app.py

@@ -57,6 +57,13 @@ def db():
     return g.db
 
 
+@app.teardown_appcontext
+def close_db(exception=None):
+    database = g.pop("db", None)
+    if database is not None:
+        database.close()
+
+
 # --- Routes ---
 
 
@@ -110,10 +117,20 @@ def drafts():
 
 @app.route("/drafts/<path:name>")
 def draft_detail(name: str):
-    detail = get_draft_detail(db(), name)
+    database = db()
+    detail = get_draft_detail(database, name)
     if not detail:
         abort(404)
-    return render_template("draft_detail.html", draft=detail)
+    # Build set of draft ref IDs that exist in our DB for internal linking
+    ref_draft_ids = [r["id"] for r in detail.get("refs", []) if r["type"] == "draft"]
+    known_drafts = set()
+    if ref_draft_ids:
+        placeholders = ",".join("?" * len(ref_draft_ids))
+        rows = database.conn.execute(
+            f"SELECT name FROM drafts WHERE name IN ({placeholders})", ref_draft_ids
+        ).fetchall()
+        known_drafts = {r["name"] for r in rows}
+    return render_template("draft_detail.html", draft=detail, known_drafts=known_drafts)
 
 
 @app.route("/ideas")
@@ -139,9 +156,9 @@ def gaps_demo():
     draft_info = None
     if selected:
         draft_text = read_generated_draft(selected)
-        for g in generated:
-            if g["filename"] == selected:
-                draft_info = g
+        for gd in generated:
+            if gd["filename"] == selected:
+                draft_info = gd
                 break
     elif generated:
         draft_info = generated[0]