docs: add AI Chat Agent documentation and update README

- doc/28-AI-CHAT-AGENT.md: comprehensive technical documentation covering
  architecture, agent design, query_cv tool, HTMX integration, graceful
  degradation, security, and example conversations
- README.md: add AI Chat Agent section with examples, ADK Go badge,
  updated tech stack and documentation index
- doc/00-GO-DOCUMENTATION-INDEX.md: add chat agent to doc index

README.md

@@ -1,7 +1,9 @@
 # CV Site - Go + HTMX
 
-[![Go Version](https://img.shields.io/badge/Go-1.21%2B-00ADD8?logo=go)](https://go.dev/)
-[![HTMX](https://img.shields.io/badge/HTMX-1.9.10-3366CC)](https://htmx.org/)
+[![Go Version](https://img.shields.io/badge/Go-1.25%2B-00ADD8?logo=go)](https://go.dev/)
+[![HTMX](https://img.shields.io/badge/HTMX-2.0-3366CC)](https://htmx.org/)
+[![ADK Go](https://img.shields.io/badge/ADK_Go-1.0-4285F4?logo=google)](https://github.com/google/adk-go)
+[![Gemini](https://img.shields.io/badge/Gemini_2.5_Flash-AI_Chat-8E75B2?logo=google)](https://aistudio.google.com/)
 [![License](https://img.shields.io/badge/License-MIT-green.svg)](LICENSE)
 
 **Modern, minimal curriculum vitae website** for Juan Andrés Moreno Rubio built with **Go** and **HTMX**.
@@ -19,6 +21,7 @@ A professional, bilingual CV site with server-side PDF generation, HTMX interact
 ## 📑 Table of Contents
 
 - [Features](#-features)
+- [AI Chat Agent](#-ai-chat-agent)
 - [Demo](#-demo)
 - [Security](#-security)
 - [Quick Start](#-quick-start)
@@ -43,6 +46,7 @@ A professional, bilingual CV site with server-side PDF generation, HTMX interact
 - ✅ **Zoom Control** - Adjustable zoom (25%-300%) with persistence across sessions
 - ✅ **Responsive** - Mobile, tablet, and desktop friendly
 - ✅ **JSON-Based Content** - Easy to update without touching code
+- ✅ **AI Chat Agent** - Ask questions about the CV in natural language (powered by ADK Go + Gemini)
 - ✅ **AI Development Section** - Showcases modern AI-assisted development skills
 - ✅ **Fast & Lightweight** - Go backend with chromedp for PDF generation
 - ✅ **Privacy-Friendly Analytics** - Self-hosted analytics (no third-party data sharing)
@@ -50,6 +54,50 @@ A professional, bilingual CV site with server-side PDF generation, HTMX interact
 - ✅ **Production Ready** - Systemd service, CI/CD workflows, deployment guides
 - ✅ **Developer Friendly** - Hot reload, clear code structure, comprehensive Makefile
 
+## 🤖 AI Chat Agent
+
+Visitors can ask questions about the CV through a floating chat widget — powered by [Google ADK Go 1.0](https://github.com/google/adk-go) and Gemini 2.5 Flash.
+
+### How It Works
+
+```
+Visitor types question → HTMX POST /api/chat → ADK Agent runs query_cv tool
+→ Tool searches cached CV JSON data → Agent formulates answer → HTML response
+```
+
+### Example Questions & Answers
+
+| Question | Answer |
+|----------|--------|
+| *"How many Go projects has Juan built?"* | Lists 2 Go projects with descriptions |
+| *"What companies has he worked at?"* | Lists all 11 companies |
+| *"Does he have React experience?"* | Shows companies where React was used |
+| *"¿Qué certificaciones tiene?"* | Lists certifications — answers in Spanish automatically |
+
+### Key Design Decisions
+
+- **Single agent, single tool** — the CV data is bounded; multi-agent orchestration would be over-engineering
+- **Reads from the same data cache** the site uses — zero data duplication, always in sync
+- **Graceful degradation** — no API key? Chat icon simply doesn't appear. Zero impact on the site
+- **HTMX-native** — `hx-post` sends messages, responses are HTML fragments, no WebSocket needed
+- **Language-aware** — the agent responds in whatever language the visitor writes in
+
+### Setup
+
+```bash
+# Get a free API key from https://aistudio.google.com/apikey
+echo "GOOGLE_API_KEY=your-key" >> .env
+
+# Chat icon appears automatically on next server start
+go run .
+```
+
+**Free tier:** 15 requests/minute — more than enough for a personal CV site.
+
+**Full technical documentation:** [doc/28-AI-CHAT-AGENT.md](doc/28-AI-CHAT-AGENT.md)
+
+---
+
 ## 📸 Demo
 
 🔗 **Live Demo:** [https://juan.andres.morenorub.io/](https://juan.andres.morenorub.io/)
@@ -187,9 +235,10 @@ No code changes needed - just refresh browser!
 
 ## 🎯 Key Technologies
 
-- **Backend:** Go 1.21+ (stdlib `net/http`, graceful shutdown)
+- **Backend:** Go 1.25+ (stdlib `net/http`, graceful shutdown)
+- **AI Agent:** Google ADK Go 1.0 + Gemini 2.5 Flash (conversational CV navigator)
 - **PDF Generation:** chromedp (headless Chrome automation)
-- **Frontend:** HTMX 1.9.10 (hypermedia-driven interactions)
+- **Frontend:** HTMX 2.0 + Hyperscript (hypermedia-driven interactions)
 - **Styling:** Custom CSS with Quicksand font from Google Fonts
 - **Data:** JSON files for easy content management
 - **Deployment:** Systemd service, manual binary, GitHub Actions CI/CD
@@ -206,6 +255,7 @@ This project includes comprehensive documentation organized by purpose:
 ### 🔧 Technical Reference
 - **[ARCHITECTURE.md](doc/ARCHITECTURE.md)** - System design, patterns, and technical decisions
 - **[API.md](doc/API.md)** - Complete HTTP API reference and HTMX integration
+- **[AI-CHAT-AGENT.md](doc/28-AI-CHAT-AGENT.md)** - ADK Go agent architecture, tool design, and integration details
 
 ### 📋 Policies & Standards
 - **[SECURITY.md](doc/9-SECURITY.md)** - Complete security architecture, implementation, and testing guide
@@ -323,6 +373,7 @@ This project is licensed under the **MIT License** - see the [LICENSE](LICENSE)
 ## 🙏 Acknowledgments
 
 - **HTMX** - For making hypermedia-driven applications enjoyable
+- **Google ADK Go** - For the production-grade agent framework
 - **chromedp** - For reliable headless Chrome automation
 - **Go Community** - For excellent standard library and tooling
 - **AI Assistance** - For accelerating development and documentation