docs(contract-validator): create documentation (#191)

Add comprehensive plugin documentation:
- README.md: Plugin overview, problem statement, tool docs,
  example workflows, issue types, best practices
- claude-md-integration.md: CLAUDE.md snippets, interface
  documentation standards, CI/CD integration guide

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

plugins/contract-validator/claude-md-integration.md

@@ -0,0 +1,152 @@
+# contract-validator Plugin - CLAUDE.md Integration
+
+Add this section to your marketplace or project's CLAUDE.md to enable contract validation features.
+
+## Suggested CLAUDE.md Section
+
+```markdown
+## Contract Validation
+
+This marketplace uses the contract-validator plugin for cross-plugin compatibility checks.
+
+### Available Commands
+
+| Command | Purpose |
+|---------|---------|
+| `/validate-contracts` | Full marketplace compatibility validation |
+| `/check-agent` | Validate single agent definition |
+| `/list-interfaces` | Show all plugin interfaces |
+
+### Validation Workflow
+
+Run before merging plugin changes:
+
+1. `/validate-contracts` - Check for conflicts
+2. Review errors (must fix) and warnings (should review)
+3. Fix issues before merging
+
+### Interface Documentation Standards
+
+For plugins to be validated correctly, document interfaces in README.md:
+
+**Commands Section:**
+```markdown
+## Commands
+
+| Command | Description |
+|---------|-------------|
+| `/my-command` | What it does |
+```
+
+**Tools Section:**
+```markdown
+## Tools Summary
+
+### Category (N tools)
+`tool_a`, `tool_b`, `tool_c`
+```
+
+**Agents Section:**
+```markdown
+## Agents
+
+| Agent | Description |
+|-------|-------------|
+| `my-agent` | What it does |
+```
+```
+
+## Declaring Agent Tool References
+
+For agent validation to work, document tool usage in CLAUDE.md:
+
+### Option 1: Four-Agent Model Table
+
+```markdown
+### Four-Agent Model
+
+| Agent | Personality | Responsibilities |
+|-------|-------------|------------------|
+| **Planner** | Methodical | Planning via `create_issue`, `search_lessons` |
+```
+
+### Option 2: Agent Sections
+
+```markdown
+### Planner Agent
+
+Uses these tools:
+- `create_issue` - Create planning issues
+- `search_lessons` - Find relevant lessons
+```
+
+## Best Practices for Plugin Authors
+
+### Unique Command Names
+
+Avoid generic names that may conflict:
+
+```markdown
+# BAD - Will conflict with other plugins
+| `/setup` | Setup wizard |
+
+# GOOD - Plugin-specific prefix
+| `/data-setup` | Data platform setup wizard |
+```
+
+### Document All Tools
+
+Ensure every MCP tool is listed in README.md:
+
+```markdown
+## Tools Summary
+
+### pandas (14 tools)
+`read_csv`, `read_parquet`, `read_json`, `to_csv`, `to_parquet`,
+`describe`, `head`, `tail`, `filter`, `select`, `groupby`, `join`,
+`list_data`, `drop_data`
+```
+
+### Specify Dependencies
+
+If agents depend on tools from other plugins, document it:
+
+```markdown
+## Dependencies
+
+This agent uses tools from:
+- `projman` - Issue management (`create_issue`, `update_issue`)
+- `data-platform` - Data loading (`read_csv`, `describe`)
+```
+
+## Typical Workflows
+
+### Pre-Merge Validation
+
+```
+# Before merging new plugin
+/validate-contracts
+
+# Check specific agent after changes
+/check-agent Orchestrator
+```
+
+### Plugin Development
+
+```
+# See what interfaces exist
+/list-interfaces
+
+# After adding new command, verify no conflicts
+/validate-contracts
+```
+
+### CI/CD Integration
+
+Add to your pipeline:
+
+```yaml
+- name: Validate Plugin Contracts
+  run: |
+    claude --skill contract-validator:validate-contracts --args "${{ github.workspace }}"
+```