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/static/css/play.css

@@ -1436,10 +1436,28 @@
 
 /* 3-column layout for chat modal with history sidebar */
 .npc-modal-body--three-col {
+    padding: 0;  /* Let container handle padding */
+    max-height: 70vh;
+}
+
+/* Apply grid to the actual container holding the three columns */
+.npc-modal-body--three-col .npc-chat-container {
     display: grid;
     grid-template-columns: 200px 1fr 280px;  /* Profile | Chat | History */
     gap: 1rem;
-    max-height: 70vh;
+    padding: 1rem 1.25rem;
+    height: 100%;
+}
+
+/* Override hardcoded widths for grid children - let grid define sizes */
+.npc-modal-body--three-col .npc-profile {
+    width: auto;
+}
+
+/* Ensure history panel is visible in modal grid */
+.npc-modal-body--three-col .npc-history-panel {
+    min-height: 200px;
+    overflow-y: auto;
 }
 
 /* NPC Profile (Left Column) */
@@ -1699,24 +1717,13 @@
     font-style: italic;
 }
 
-/* HTMX Loading Indicator */
+/* HTMX Loading Indicator - visible by default, replaced by HTMX response */
 .history-loading {
     text-align: center;
     color: var(--text-muted);
     font-size: 0.875rem;
     padding: 1rem 0;
     font-style: italic;
-    display: none;
-}
-
-/* Show loading indicator when HTMX is making a request */
-.htmx-indicator.htmx-request .history-loading {
-    display: block;
-}
-
-/* Hide other content while loading */
-.htmx-indicator.htmx-request > *:not(.history-loading) {
-    opacity: 0.5;
 }
 
 /* Responsive NPC Modal */
@@ -1763,20 +1770,23 @@
 
 /* Responsive: 3-column modal stacks on smaller screens */
 @media (max-width: 1024px) {
-    .npc-modal-body--three-col {
+    .npc-modal-body--three-col .npc-chat-container {
         grid-template-columns: 1fr;  /* Single column */
         grid-template-rows: auto 1fr auto;
     }
 
-    .npc-profile {
+    .npc-modal-body--three-col .npc-profile {
         order: 1;
+        width: 100%;
+        flex-direction: row;
+        flex-wrap: wrap;
     }
 
-    .npc-conversation {
+    .npc-modal-body--three-col .npc-conversation {
         order: 2;
     }
 
-    .npc-history-panel {
+    .npc-modal-body--three-col .npc-history-panel {
         order: 3;
         border-left: none;
         border-top: 1px solid var(--play-border);