fix(web): restore 3-column NPC chat modal layout for desktop

- Fixed grid layout not applying to modal content (grid was on wrong parent element)
- Applied grid to .npc-chat-container instead of .npc-modal-body--three-col
- Removed htmx-indicator class from history panel (was causing content to disappear)
- Made history loading indicator visible by default
- Updated responsive breakpoints to target correct selectors
- Added warning to HTMX_PATTERNS.md about htmx-indicator hidden behavior

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

public_web/templates/game/partials/npc_chat_content.html

@@ -109,7 +109,7 @@ Displays NPC profile, conversation interface, and message history
     </div>
 
     {# Right Column: Message History Sidebar #}
-    <aside class="npc-history-panel htmx-indicator"
+    <aside class="npc-history-panel"
            id="npc-history-{{ npc.npc_id }}"
            hx-get="{{ url_for('game.npc_chat_history', session_id=session_id, npc_id=npc.npc_id) }}"
            hx-trigger="load, newMessage from:body"