fix: match CV design system, right-side positioning, smarter agent

CSS:
- Button moved to right: 2rem, above back-to-top (bottom: 6rem)
- Uses CV design tokens: --black-bar, --accent-blue, --paper-bg
- Fonts: Quicksand (header), Source Sans Pro (body)
- Tooltip on the left side (tooltip-left class)
- Dark theme uses CV-consistent grays

Intelligence:
- Agent instruction emphasizes exhaustive reporting of ALL matches
- Cross-section search results must not be truncated
- Mentions CV site itself is built with Go when relevant

Tests:
- Updated positioning assertions (right side, x > viewport/2)
- Added 5 intelligence tests: Go cross-section, company count,
  years of experience, React cross-section, Spanish response
- Resilient to API errors (waits for any message, not just user)
- 42 total test assertions

templates/partials/widgets/chat-widget.html

@@ -3,7 +3,7 @@
 <!-- AI Chat Widget — CV Assistant Mascot -->
 <button
     id="chat-toggle-btn"
-    class="fixed-btn chat-toggle-btn no-print has-tooltip"
+    class="fixed-btn chat-toggle-btn no-print has-tooltip tooltip-left"
     aria-label="{{if eq .Lang "es"}}Asistente del CV{{else}}CV Assistant{{end}}"
     data-tooltip="{{if eq .Lang "es"}}Asistente del CV{{else}}CV Assistant{{end}}"
     _="on click toggle .chat-open on #chat-panel