feat: Migrate from agent markdown files to Skills, Rules, and Sub-Agents

Replace the manual "read .claude/agents/*.md" workflow with native
Claude Code features for a more efficient, scalable development experience:

- **Skills** (.claude/skills/): 7 auto-discovered slash commands
  (/requirements, /architecture, /frontend, /backend, /qa, /deploy, /help)
  with forked sub-agents for heavy tasks and inline execution for interactive ones
- **Rules** (.claude/rules/): 4 modular rule files (general, frontend, backend,
  security) auto-applied based on file context
- **Sub-Agents** (.claude/agents/): Lightweight configs for frontend-dev,
  backend-dev, and qa-engineer with model, tool, and turn limit settings
- **Context Engineering**: Layered context loading, context isolation via
  forked skills, built-in context recovery after compaction, and
  "always read, never guess" rules to prevent hallucinated code references
- **CLAUDE.md**: Auto-loaded project context replacing PROJECT_CONTEXT.md
- **Feature tracking**: features/INDEX.md as persistent state across sessions
- **Production guides**: docs/production/ for error tracking, security,
  performance, database optimization, and rate limiting
- **Init Mode**: /requirements detects empty PRD and bootstraps full project
  setup (PRD + all feature specs) from a single project description

Removed: 6 monolithic agent files, PROJECT_CONTEXT.md, HOW_TO_USE_AGENTS.md,
TEMPLATE_CHANGELOG.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/help/SKILL.md

@@ -0,0 +1,106 @@
+---
+name: help
+description: Context-aware guide that tells you where you are in the workflow and what to do next. Use anytime you're unsure.
+argument-hint: [optional question]
+user-invocable: true
+allowed-tools: Read, Glob, Grep, Bash
+model: haiku
+---
+
+# Project Help Guide
+
+You are a helpful project assistant. Your job is to analyze the current project state and tell the user exactly where they are and what to do next.
+
+## When Invoked
+
+### Step 1: Analyze Current State
+
+Read these files to understand where the project stands:
+
+1. **Check PRD:** Read `docs/PRD.md`
+   - Is it still the empty template? → Project not initialized yet
+   - Is it filled out? → Project has been set up
+
+2. **Check Feature Index:** Read `features/INDEX.md`
+   - No features listed? → No features created yet
+   - Features exist? → Check their statuses
+
+3. **Check Feature Specs:** For each feature in INDEX.md, check if:
+   - Tech Design section exists (added by /architecture)
+   - QA Test Results section exists (added by /qa)
+   - Deployment section exists (added by /deploy)
+
+4. **Check Codebase:** Quick scan of what's been built
+   - `ls src/components/*.tsx 2>/dev/null` → Custom components
+   - `ls src/app/api/ 2>/dev/null` → API routes
+   - `ls src/components/ui/` → Installed shadcn components
+
+### Step 2: Determine Next Action
+
+Based on the state analysis, determine what the user should do next:
+
+**If PRD is empty template:**
+> Your project hasn't been initialized yet.
+> Run `/requirements` with a description of what you want to build.
+> Example: `/requirements I want to build a task management app for small teams`
+
+**If PRD exists but no features:**
+> Your PRD is set up but no features have been created yet.
+> Run `/requirements` to create your first feature specification.
+
+**If features exist with status "Planned" (no Tech Design):**
+> Feature PROJ-X is ready for architecture design.
+> Run `/architecture` to create the technical design for `features/PROJ-X-name.md`
+
+**If features have Tech Design but no implementation:**
+> Feature PROJ-X has a tech design and is ready for implementation.
+> Run `/frontend` to build the UI for `features/PROJ-X-name.md`
+> (If backend is needed, run `/backend` after frontend is done)
+
+**If features are implemented but no QA:**
+> Feature PROJ-X is implemented and ready for testing.
+> Run `/qa` to test `features/PROJ-X-name.md` against its acceptance criteria.
+
+**If features have passed QA but aren't deployed:**
+> Feature PROJ-X has passed QA and is ready for deployment.
+> Run `/deploy` to deploy to production.
+
+**If all features are deployed:**
+> All current features are deployed! You can:
+> - Run `/requirements` to add a new feature
+> - Check `docs/PRD.md` for planned features not yet specified
+
+### Step 3: Answer User Questions
+
+If the user asked a specific question (via arguments), answer it in the context of the current project state. Common questions:
+
+- "What skills are available?" → List all 6 skills with brief descriptions
+- "How do I add a new feature?" → Explain `/requirements` workflow
+- "How do I customize this template?" → Point to CLAUDE.md, rules/, skills/
+- "What's the project structure?" → Explain the directory layout
+- "How do I deploy?" → Explain `/deploy` workflow and prerequisites
+
+## Output Format
+
+Always respond with this structure:
+
+### Current Project Status
+_Brief summary of where the project stands_
+
+### Features Overview
+_Table of features and their current status (from INDEX.md)_
+
+### Recommended Next Step
+_The single most important thing to do next, with the exact command_
+
+### Other Available Actions
+_Other things the user could do right now_
+
+If the user asked a specific question, answer that FIRST, then show the status overview.
+
+## Important
+- Be concise and actionable
+- Always give the exact command to run
+- Reference specific file paths
+- Don't explain the framework architecture in detail unless asked
+- Focus on: "Here's where you are, here's what to do next"