feat(02-01): /gsd:map-codebase command and workflow skeleton

- commands/gsd/map-codebase.md: slash command entry point
- get-shit-done/workflows/map-codebase.md: workflow with 6 process steps
- Documents 4 parallel Explore agents and 7 output files
- Agent orchestration to be implemented in plan 02-02

commands/gsd/map-codebase.md

@@ -0,0 +1,85 @@
+---
+description: Analyze codebase with parallel Explore agents to produce .planning/codebase/ documents
+argument-hint: "[optional: specific area to map, e.g., 'api' or 'auth']"
+allowed-tools:
+  - Read
+  - Bash
+  - Glob
+  - Grep
+  - Write
+  - Task
+---
+
+<objective>
+Analyze existing codebase using parallel Explore agents to produce structured codebase documents.
+
+This command spawns multiple Explore agents to analyze different aspects of the codebase in parallel, each with fresh context. Each agent produces focused documentation under 100 lines.
+
+Output: .planning/codebase/ folder with 7 structured documents about the codebase state.
+</objective>
+
+<execution_context>
+@~/.claude/get-shit-done/workflows/map-codebase.md
+@~/.claude/get-shit-done/templates/codebase/stack.md
+@~/.claude/get-shit-done/templates/codebase/architecture.md
+@~/.claude/get-shit-done/templates/codebase/structure.md
+@~/.claude/get-shit-done/templates/codebase/conventions.md
+@~/.claude/get-shit-done/templates/codebase/testing.md
+@~/.claude/get-shit-done/templates/codebase/integrations.md
+@~/.claude/get-shit-done/templates/codebase/concerns.md
+</execution_context>
+
+<context>
+Focus area: $ARGUMENTS (optional - if provided, tells agents to focus on specific subsystem)
+
+**Load project state if exists:**
+Check for .planning/STATE.md - loads context if project already initialized
+
+**This command can run:**
+- Before /gsd:new-project (brownfield codebases) - creates codebase map first
+- After /gsd:new-project (greenfield codebases) - updates codebase map as code evolves
+- Anytime to refresh codebase understanding
+</context>
+
+<when_to_use>
+**Use map-codebase for:**
+- Brownfield projects before initialization (understand existing code first)
+- Refreshing codebase map after significant changes
+- Onboarding to an unfamiliar codebase
+- Before major refactoring (understand current state)
+- When STATE.md references outdated codebase info
+
+**Skip map-codebase for:**
+- Greenfield projects with no code yet (nothing to map)
+- Trivial codebases (<5 files)
+</when_to_use>
+
+<process>
+1. Check if .planning/codebase/ already exists (offer to refresh or skip)
+2. Create .planning/codebase/ directory structure
+3. Spawn 4 parallel Explore agents to analyze codebase:
+   - Agent 1: Stack + Integrations (technology focus)
+   - Agent 2: Architecture + Structure (organization focus)
+   - Agent 3: Conventions + Testing (quality focus)
+   - Agent 4: Concerns (issues focus)
+4. Wait for all agents to complete, collect findings
+5. Write 7 codebase documents using templates:
+   - STACK.md - Languages, frameworks, key dependencies
+   - ARCHITECTURE.md - System design, patterns, data flow
+   - STRUCTURE.md - Directory layout, module organization
+   - CONVENTIONS.md - Code style, naming, patterns
+   - TESTING.md - Test structure, coverage, practices
+   - INTEGRATIONS.md - APIs, databases, external services
+   - CONCERNS.md - Technical debt, risks, issues
+6. Verify each document is under 100 lines (summarize if needed)
+7. Offer next steps (typically: /gsd:new-project or /gsd:plan-phase)
+</process>
+
+<success_criteria>
+- [ ] .planning/codebase/ directory created
+- [ ] All 7 codebase documents written
+- [ ] Each document under 100 lines
+- [ ] Documents follow template structure
+- [ ] Parallel agents completed without errors
+- [ ] User knows next steps
+</success_criteria>