feat: debug template upgrade, 5 new agent templates, game fixes

- Upgraded Debug This Error to 3-phase pipeline (triage → root cause → verify)
- Added 14-pattern common-fix lookup table and DO/DON'T rules
- New agent: Performance Profiler (N+1, memory leaks, O(n²), caching)
- New agent: Implementation Planner (feature→phased plan + risk assessment)
- New agent: Git Commit Reviewer (diff→conventional commits + changelog)
- New agent: Deployment Checklist (stack→CI/CD + Docker + rollback)
- New agent: Cost-Aware LLM Pipeline (model routing + budget tracking)
- Fixed game emoji encoding, localStorage sandbox, Breakout touch events
- Added Canvas 2D arcade game templates (platformer, shooter, rhythm, puzzle, tower defense)
- Updated README release notes

Author: ijbo

README.md

@@ -458,8 +458,11 @@ TextAgent has undergone significant evolution since its inception. What started
 ## 📋 Release Notes
 
 | Date | Commits | Feature / Update |
-|------|---------|-----------------|
-| **2026-03-16** | | 📄 **Page View (A4 Document Mode)** — new split-layout "Page" view mode (editor left, A4 page frames right) with automatic content reflow into 210×297mm page frames; `<!-- pagebreak -->` HTML comment markers force new pages; page counter, zoom dropdown (50%–125%), and Export PDF button in page header; `page-view.js` reflow engine measures element heights and distributes across pages; `page-view.css` with shadows, page numbers, dark mode, responsive mobile; button added to header/mobile/QAB; `setViewMode()` extended with `view-page` class and enter/exit lifecycle |
+|------|---------|-----------------:|
+| **2026-03-16** | | 🐛 **Debug Template Upgrade** — upgraded "Debug This Error" from single-pass AI prompt to 3-phase pipeline (Triage & Classify with 14-pattern common-fix lookup table → Root Cause & Fix with before/after diffs and DO/DON'T rules → Verify & Prevent via Agent multi-step with verification commands, preventive guard code, and related-issue sweep); added `language` and `codeSnippet` variables |
+| **2026-03-16** | | 🤖 **5 New Agent Templates** — Performance Profiler (N+1 detection, memory leaks, O(n²) loops, caching strategy), Implementation Planner (feature→phased plan with task breakdown, risk assessment), Git Commit Reviewer (diff→conventional commits, breaking change detection, changelog), Deployment Checklist (stack→CI/CD pipeline, Docker config, rollback plan), Cost-Aware LLM Pipeline (model routing, budget tracking, fallback strategies) |
+| **2026-03-16** | | 🎮 **Game Template Fixes** — fixed emoji encoding (HTML entities→native Unicode), wrapped localStorage in try/catch for sandboxed iframes, added Breakout touch events for mobile, removed duplicate code blocks from game template, added `allow-same-origin` to game iframe sandbox, added Canvas 2D arcade game templates (platformer, top-down shooter, rhythm, tile match, tower defense) |
+| **2026-03-16** | | 📄 **Page View (A4 Document Mode)** — new split-layout "Page" view mode (editor left, A4 page frames right) with automatic content reflow into 210×297mm page frames; `<!-- pagebreak -->` HTML comment markers force new pages; `page-view.js` reflow engine measures element heights and distributes across pages; `page-view.css` with shadows, page numbers, dark mode, responsive mobile; button added to header/mobile/QAB; `setViewMode()` extended with `view-page` class and enter/exit lifecycle |
 | **2026-03-16** | | 🛡️ **Security Scan Upgrade & ECC-Inspired Agents** — upgraded Security Scan from single-pass OWASP checklist to 3-step pipeline (Vulnerability Scan → Attack Simulation → Remediation Plan) with language/framework/scanDepth variables, ❌/✅ code patterns, A-F grading, and pre-deployment checklist; added 5 new ECC-inspired agent templates (TDD Guide, Database Review, Generate E2E Tests, API Design Review, Fix Build Errors) |
 | **2026-03-16** | | 🤖 **Agent Templates Tab** — new Agents category with 9 specialized AI agent templates (Plan a Feature, Review My Code, Security Scan, Clean Up Code, Generate Docs, Python Review, Design Architecture, Debug This Error, SQL Optimizer); `bi-robot` icon; category pill in template modal; multi-step Agent pipelines with contextual variables |
 | **2026-03-16** | | 📄 **Page View Mode** — new A4-style paginated document preview with `<!-- pagebreak -->` support; `page-view.js` + `page-view.css` modules; `data-pagebreak` renderer support |