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

templates/partials/widgets/chat-widget.html

@@ -24,25 +24,12 @@
         <span>{{if eq .Lang "es"}}Asistente del CV{{else}}CV Assistant{{end}}</span>
         <button class="chat-help-btn"
             aria-label="{{if eq .Lang "es"}}Ayuda{{else}}Help{{end}}"
-            _="on click toggle .visible on #chat-help-card">
+            commandfor="chat-help-modal"
+            command="show-modal">
             <iconify-icon icon="mdi:help-circle-outline"></iconify-icon>
         </button>
     </div>
 
-    <!-- Help / Onboarding Card -->
-    <div id="chat-help-card" class="chat-help-card visible">
-        <div class="chat-help-icon">
-            <iconify-icon icon="mdi:robot-happy-outline"></iconify-icon>
-        </div>
-        <p class="chat-help-text">
-            {{if eq .Lang "es"}}¡Soy el Asistente del CV! Puedo responder preguntas sobre la experiencia profesional, proyectos, habilidades y formación de Juan. Prueba a hacer clic en una sugerencia o escribe tu propia pregunta.{{else}}I'm the CV Assistant! I can answer questions about Juan's professional experience, projects, skills, and education. Try clicking a suggestion or type your own question.{{end}}
-        </p>
-        <button class="chat-help-dismiss"
-            _="on click remove .visible from #chat-help-card">
-            {{if eq .Lang "es"}}Entendido{{else}}Got it{{end}}
-        </button>
-    </div>
-
     <div id="chat-messages" class="chat-messages">
         <div class="chat-message chat-agent">
             {{if eq .Lang "es"}}¡Hola! Pregúntame lo que quieras sobre este CV.{{else}}Hi! Ask me anything about this CV.{{end}}