feat: aguara check and aguara clean commands

[garagon]

Summary

Two new incident response commands for detecting and cleaning compromised Python packages.

Built in response to the litellm supply chain attack (March 24, 2026). Detection rules alone aren't enough - users need to check if they're affected and clean up.

aguara check

Scans installed Python environments for compromised packages and persistence artifacts.

aguara check                          # auto-discover Python env
aguara check --path /opt/venv/lib/python3.12/site-packages/
aguara check --include-caches         # also check pip/uv caches
aguara check --format json            # machine-readable output

Detects:

• Known compromised package versions (embedded database, currently litellm 1.82.7/1.82.8)
• .pth files with executable content (import, subprocess, exec, eval)
• Persistence artifacts (systemd services, sysmon backdoor)
• Reports which credential files exist and need rotation

aguara clean

Removes compromised packages and quarantines malicious files.

aguara clean --dry-run                # preview without changes
aguara clean                          # interactive confirmation
aguara clean --yes                    # skip confirmation
aguara clean --purge-caches           # also purge pip/uv caches

Actions:

• Uninstalls compromised packages via pip/uv
• Quarantines .pth files to /tmp/aguara-quarantine/ (forensic evidence)
• Disables systemd persistence services
• Prints credential rotation checklist

Files added

• cmd/aguara/commands/check.go - check command (terminal + JSON output)
• cmd/aguara/commands/clean.go - clean command (dry-run, quarantine, confirmation)
• internal/incident/compromised.go - embedded known-bad package list
• internal/incident/checker.go - package detection, .pth scanning, persistence check
• internal/incident/cleaner.go - removal, quarantine, cache purge
• internal/incident/checker_test.go - 9 tests
• internal/incident/cleaner_test.go - 5 tests

Test plan

• 14 new tests, all passing with -race
• Full test suite: 574 tests, 0 lint issues
• Detects compromised litellm in fake site-packages
• Detects malicious .pth files
• Does not flag legitimate .pth files (path-only content)
• Dry run shows actions without executing
• Quarantine moves files, doesn't delete
• Clean environment produces clean result
• JSON output works for both commands