docs: add multi-machine setup guide

Add comprehensive guide for using this config across multiple machines
(personal, work, etc.) without branch conflicts.

Changes:
- Add MULTI-MACHINE-SETUP.md with complete setup instructions
- Add CLAUDE-LOCAL.md.example as template for machine-specific overrides
- Update .gitignore to exclude CLAUDE-LOCAL.md and *-local.json patterns
- Update README.md to reference multi-machine setup guide

Key features:
- Layered configuration approach (shared + local overrides)
- No branch conflicts - local overrides are git-ignored
- Same repo works with different Claude Code credentials
- Supports work/personal machines with different standards

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

CLAUDE-LOCAL.md.example

@@ -0,0 +1,155 @@
+# Local Overrides Example
+
+This is an example file. Copy to `CLAUDE-LOCAL.md` to use:
+
+```bash
+cp CLAUDE-LOCAL.md.example CLAUDE-LOCAL.md
+vim CLAUDE-LOCAL.md  # Customize for this machine
+```
+
+`CLAUDE-LOCAL.md` will NOT be tracked in git (excluded by .gitignore).
+
+---
+
+# Local Overrides - [Machine Name/Purpose]
+
+Last updated: 2025-11-26
+
+This file contains machine-specific preferences that override or extend
+CLAUDE.md. It is NOT tracked in git.
+
+## Machine Context
+
+- **Purpose**: [Personal/Work/Research/etc.]
+- **Primary languages**: [Additional languages beyond CLAUDE.md]
+- **Authentication**: [Company/Personal Claude Code account]
+- **Operating System**: [If different from Gentoo]
+
+## Company-Specific Standards (for Work Machines)
+
+### Commit Message Format
+
+Override the format in CLAUDE.md for company requirements:
+
+```
+[TICKET-123] type: description
+
+Examples:
+[PROJ-456] feat: add user authentication
+[BUG-789] fix: resolve memory leak in parser
+```
+
+### Code Review Process
+
+- All PRs require 2 approvals
+- Use company GitHub Enterprise: github.company.com
+- PR template required
+- CI must pass: Jenkins pipeline
+
+### Testing Requirements
+
+- Minimum 80% code coverage
+- Integration tests required for API changes
+- Use company test fixtures: `@company/test-utils`
+
+### Deployment
+
+- Dev: dev.company.internal
+- Staging: staging.company.internal
+- Production: company.com
+- Deploy via Jenkins: jenkins.company.internal
+
+## Internal Resources (for Work Machines)
+
+### Documentation
+- API docs: https://api-docs.company.internal
+- Architecture decisions: https://wiki.company.com/adr
+- Style guide: https://styleguide.company.com
+- Onboarding: https://wiki.company.com/onboarding
+
+### Tools
+- Issue tracker: jira.company.com
+- Code review: github.company.com
+- CI/CD: jenkins.company.internal
+- Monitoring: grafana.company.internal
+
+## Additional Languages/Tools
+
+If this machine uses languages not in CLAUDE.md:
+
+### Java
+- Style: Google Java Style Guide
+- Build: Maven (follow company pom.xml template)
+- Testing: JUnit 5 + Mockito
+
+### Go
+- Style: Follow gofmt + company conventions
+- Testing: standard testing package
+- Linting: golangci-lint
+
+## Project-Specific Context
+
+### Current Projects
+- **Project A**: [Brief description, repo URL]
+- **Project B**: [Brief description, repo URL]
+
+### Local Development Setup
+- Docker registry: registry.company.internal:5000
+- Database: postgres://localhost:5432/dev
+- Redis: localhost:6379
+
+## Machine-Specific Paths
+
+- **Work repos**: ~/work/repos/
+- **Company tools**: ~/work/tools/
+- **Certificates**: ~/work/certs/
+- **VPN config**: ~/work/vpn/
+
+## Network/Infrastructure
+
+### VPN
+- Connect before git operations: `vpn-connect company`
+- All internal resources require VPN
+
+### SSH Keys
+- Work key: ~/.ssh/id_ed25519_work
+- GitHub config:
+  ```
+  Host github.company.com
+    HostName github.company.com
+    User git
+    IdentityFile ~/.ssh/id_ed25519_work
+  ```
+
+## Security & Compliance
+
+### Secrets Management
+- Use company vault: vault.company.internal
+- Never commit secrets (same as CLAUDE.md)
+- Use environment variables from company secrets manager
+
+### Compliance
+- GDPR compliance required for user data
+- Follow company security hardening guide
+- All dependencies must pass security scan
+
+## Overrides Summary
+
+Quick reference of what's different on this machine:
+
+| Setting | CLAUDE.md | This Machine |
+|---------|-----------|--------------|
+| Commit format | `type: PHASE - desc` | `[TICKET] type: desc` |
+| Git remote | Personal repos | Company GitHub Enterprise |
+| Review process | N/A | 2 approvals required |
+| Deployment | N/A | Via Jenkins |
+| Code coverage | Pragmatic | Minimum 80% |
+
+## Additional Notes
+
+[Any other context Claude should know about this machine]
+
+---
+
+**Remember**: This file is machine-specific and should never be committed to
+git. It's already excluded by `.gitignore`.