fix: restore tooltip, accent-blue colors, fix chip click mechanism

- Restore has-tooltip tooltip-left on toggle button
- Use --accent-blue (#0066cc) as secondary color: header, user bubbles,
  send button, chip hover, input focus — breaks the all-black monotony
- Dark theme uses deeper blue (#003d7a header, #004d99 interactions)
- Fix chip click: replace Hyperscript htmx.trigger() call with direct
  onclick using JS htmx.trigger() — Hyperscript couldn't resolve the
  HTMX global properly
- Remove _chat.css @import from main.css (loaded separately already)

static/css/04-interactive/_chat.css

@@ -81,7 +81,7 @@
 }
 
 /* ==========================================================================
-   Header — uses black-bar like action bar
+   Header — accent-blue for visual distinction
    ========================================================================== */
 
 .chat-header {
@@ -89,8 +89,8 @@
     align-items: center;
     gap: 8px;
     padding: 10px 14px;
-    background: var(--black-bar, #2b2b2b);
-    color: var(--action-bar-text, #ffffff);
+    background: var(--accent-blue, #0066cc);
+    color: #ffffff;
     font-family: 'Quicksand', sans-serif;
     font-size: 0.85rem;
     font-weight: 600;
@@ -167,7 +167,7 @@
 }
 
 .chat-user {
-    background: var(--black-bar, #2b2b2b);
+    background: var(--accent-blue, #0066cc);
     color: #fff;
     align-self: flex-end;
     border-bottom-right-radius: 2px;
@@ -243,9 +243,9 @@
 }
 
 .chat-chip:hover {
-    background: var(--black-bar, #2b2b2b);
+    background: var(--accent-blue, #0066cc);
     color: #fff;
-    border-color: var(--black-bar, #2b2b2b);
+    border-color: var(--accent-blue, #0066cc);
 }
 
 /* ==========================================================================
@@ -279,7 +279,7 @@
 }
 
 .chat-send-btn {
-    background: var(--black-bar, #2b2b2b);
+    background: var(--accent-blue, #0066cc);
     color: #fff;
     border: none;
     border-radius: 50%;
@@ -295,7 +295,7 @@
 }
 
 .chat-send-btn:hover {
-    background: var(--accent-blue, #0066cc);
+    background: #004d99;
 }
 
 /* ==========================================================================
@@ -332,7 +332,7 @@
 }
 
 .theme-clean .chat-header {
-    background: #111111;
+    background: #003d7a;
 }
 
 .theme-clean .chat-agent {
@@ -341,7 +341,7 @@
 }
 
 .theme-clean .chat-user {
-    background: #333333;
+    background: #004d99;
 }
 
 .theme-clean .chat-error {
@@ -372,9 +372,9 @@
 }
 
 .theme-clean .chat-chip:hover {
-    background: #333333;
+    background: #004d99;
     color: #fff;
-    border-color: #333333;
+    border-color: #004d99;
 }
 
 .theme-clean .chat-typing-dot {