Fix ~50 errcheck warnings across the codebase:
- Add explicit `_ =` for intentionally ignored error returns (cleanup,
best-effort operations, etc.)
- Use `defer func() { _ = ... }()` pattern for defer statements
- Handle tmux SetEnvironment, KillSession, SendKeysRaw returns
- Handle mail router.Send returns
- Handle os.RemoveAll, os.Rename in cleanup paths
- Handle rand.Read returns for ID generation
- Handle fmt.Fprint* returns when writing to io.Writer
- Fix for-select with single case to use for-range
- Handle cobra MarkFlagRequired returns
All tests pass. Code compiles without errors.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Add doctor package with:
- Check interface for implementing health checks
- CheckContext for passing context to checks
- CheckResult and CheckStatus types
- Report with summary and pretty printing
- Doctor runner with Run() and Fix() methods
- BaseCheck and FixableCheck for easy check implementation
- CLI command: gt doctor [--fix] [--verbose] [--rig <name>]
Built-in checks will be added in:
- gt-f9x.5: Town-level checks (config, state, mail, rigs)
- gt-f9x.6: Rig-level checks (refinery, clones, gitignore)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
