rare-elite enemies + freetext notes tool + clear-confirmation

- classification 5 (rare-elite) now renders with silver-blue skull pin and shows up in the boss list with a 'rare' tag (was falling through to default trash style)
- new Note tool: click map → enter text → drops yellow info pin; hover for tooltip, double-click to edit, drag to move, right-click to remove. Notes are included in the share-URL hash and history.
- Clear button now confirms before wiping the current floor's waypoints/pulls/notes

web/index.html

@@ -31,6 +31,7 @@
     <div class="toolbar">
       <button id="tool-route" class="tool active" title="Click map to add waypoints">Route</button>
       <button id="tool-pull" class="tool" title="Click map to drop pull markers">Pull</button>
+      <button id="tool-note" class="tool" title="Click map to drop a note (info icon, hover to read; double-click to edit)">Note</button>
       <button id="undo" title="Undo (⌘Z)">Undo</button>
       <button id="clear" title="Clear current floor">Clear</button>
       <button id="share">Share</button>