refactor: extract skills from commands across 8 plugins

Refactored commands to extract reusable skills following the
Commands → Skills separation pattern. Each command is now <50 lines
and references skill files for detailed knowledge.

Plugins refactored:
- claude-config-maintainer: 5 commands → 7 skills
- code-sentinel: 3 commands → 2 skills
- contract-validator: 5 commands → 6 skills
- data-platform: 10 commands → 6 skills
- doc-guardian: 5 commands → 6 skills (replaced nested dir)
- git-flow: 8 commands → 7 skills

Skills contain: workflows, validation rules, conventions,
reference data, tool documentation

Commands now contain: YAML frontmatter, agent assignment,
skills list, brief workflow steps, parameters

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

plugins/git-flow/commands/git-config.md

@@ -1,106 +1,50 @@
+---
+name: git-config
+description: Configure git-flow settings for the current project
+agent: git-assistant
+---
+
 # /git-config - Configure git-flow
 
-## Visual Output
+## Skills
 
-When executing this command, display the plugin header:
-
-```
-┌──────────────────────────────────────────────────────────────────┐
-│  🔀 GIT-FLOW · Configuration                                      │
-└──────────────────────────────────────────────────────────────────┘
-```
-
-Then proceed with the configuration.
+- skills/visual-header.md
+- skills/environment-variables.md
+- skills/workflow-patterns/branching-strategies.md
 
 ## Purpose
 
-Configure git-flow settings for the current project.
+Configure git-flow settings interactively or display current configuration.
 
-## Behavior
+## Parameters
 
-### Interactive Configuration
+| Parameter | Description |
+|-----------|-------------|
+| `--show` | Display current settings without prompting |
+| `--reset` | Reset all settings to defaults |
+| `<key>=<value>` | Set specific variable directly |
 
-```
-git-flow Configuration
-═══════════════════════════════════════════
+## Workflow
 
-Current settings:
-  GIT_WORKFLOW_STYLE: feature-branch
-  GIT_DEFAULT_BASE: development
-  GIT_AUTO_DELETE_MERGED: true
-  GIT_AUTO_PUSH: false
+1. **Display header** - Show GIT-FLOW Configuration header
+2. **Load current settings** - Read from project and user config
+3. **Present menu** - Show configuration options
+4. **Handle selection** - Configure workflow style, base branch, protected branches, etc.
+5. **Save settings** - Write to `.env` or `.claude/settings.json`
+6. **Confirm** - Display saved configuration
 
-What would you like to configure?
-1. Workflow style
+## Configuration Menu
+
+1. Workflow style (simple, feature-branch, pr-required, trunk-based)
 2. Default base branch
 3. Auto-delete merged branches
 4. Auto-push after commit
 5. Protected branches
 6. View all settings
 7. Reset to defaults
-```
-
-### Setting: Workflow Style
-
-```
-Choose your workflow style:
-
-1. simple
-   - Direct commits to development
-   - No feature branches required
-   - Good for solo projects
-
-2. feature-branch (Recommended)
-   - Feature branches from development
-   - Merge when complete
-   - Good for small teams
-
-3. pr-required
-   - Feature branches from development
-   - Requires PR for merge
-   - Good for code review workflows
-
-4. trunk-based
-   - Short-lived branches
-   - Frequent integration
-   - Good for CI/CD heavy workflows
-```
-
-### Setting: Protected Branches
-
-```
-Protected branches (comma-separated):
-Current: main, master, development, staging, production
-
-These branches will:
-- Never be auto-deleted
-- Require confirmation before direct commits
-- Warn before force push
-```
-
-## Environment Variables
-
-| Variable | Default | Options |
-|----------|---------|---------|
-| `GIT_WORKFLOW_STYLE` | `feature-branch` | simple, feature-branch, pr-required, trunk-based |
-| `GIT_DEFAULT_BASE` | `development` | Any branch name |
-| `GIT_AUTO_DELETE_MERGED` | `true` | true, false |
-| `GIT_AUTO_PUSH` | `false` | true, false |
-| `GIT_PROTECTED_BRANCHES` | `main,master,development,staging,production` | Comma-separated |
-| `GIT_COMMIT_STYLE` | `conventional` | conventional, simple, detailed |
-| `GIT_CO_AUTHOR` | `true` | true, false |
-
-## Storage
-
-Settings are stored in:
-- Project: `.env` or `.claude/settings.json`
-- User: `~/.config/claude/git-flow.env`
-
-Project settings override user settings.
 
 ## Output
 
-After configuration:
 ```
 Configuration saved!