feat: help modal, comprehensive intelligence, fix right-side position

Position fix:
- Remove _chat.css @import from main.css (was overriding with old
  left:2rem cached version). Chat CSS now loaded only via head-styles.
- Button confirmed at right:2rem, bottom:6rem (above back-to-top)

Help modal:
- New chat-help-modal.html using same <dialog> pattern as shortcuts
- 6 organized categories: Experience, Technologies, Projects,
  Education, Skills, How it works
- Bilingual EN/ES with example questions per category
- ? button in header opens modal via commandfor/show-modal
- Removed inline help card (modal replaces it)

Intelligence:
- Comprehensive query strategy for 8 question types
- Technology queries always use cross-section search
- Company queries use experience without filter for full listing
- Agent knows CV site is built with Go/HTMX (bonus context)
- Skills report proficiency levels when technology found

static/css/main.css

@@ -36,7 +36,7 @@
 @import './04-interactive/_zoom-control.css';
 @import './04-interactive/_contact-form.css';
 @import './04-interactive/_sprites.css';
-@import './04-interactive/_chat.css';
+/* Chat CSS loaded separately via head-styles.html (only when ChatEnabled) */
 
 /* 05 - Responsive */
 @import './05-responsive/_breakpoints.css';