feat(plugins): implement 4 spec-only plugins

[outdoorsea]

Summary

Four plugins had complete specifications in plugin.md but no executable run.sh. This PR adds implementations for all four, following the existing plugin pattern (cooldown gate, bd wisp recording, escalation on failure).

• stuck-agent-dog (5m cooldown): Context-aware stuck/crashed agent detection for polecats and deacon. Checks tmux session + process health, notifies witness for restarts, escalates on mass death (>=3 agents). Scoped to polecats and deacon only — never touches crew, mayor, witness, or refinery sessions.

• rebuild-gt (1h cooldown): Safe binary rebuild from gastown source. Uses gt stale --json to verify staleness and forward-safety before building. Only rebuilds on main branch — prevents the crash-loop incident where a bad rebuild broke every session's startup hook.

• git-hygiene (12h cooldown): Stale branch, stash, and gc cleanup across all rig repos. Deletes merged local branches, orphan agent branches (polecat/*, dog/*, fix/*) with no remote tracking branch, merged remote branches on GitHub via gh api, clears stashes, and runs git gc --prune=now.

• dolt-snapshots: Build/run wrapper for the existing Go binary (main.go) that tags Dolt databases at convoy boundaries for audit, diff, and rollback.

Test plan

• bash -n syntax check passes for all 4 scripts
• stuck-agent-dog: correctly enumerates polecats from rigs.json, detects dead sessions, skips crew
• rebuild-gt: skips when binary is fresh, skips when safe_to_rebuild=false, rebuilds when stale+safe
• git-hygiene: deletes merged branches, preserves main/master/refinery-patrol, runs gc
• dolt-snapshots: builds Go binary and executes it

🤖 Generated with Claude Code

[codecov-commenter]

❌ 5 Tests Failed:

Tests completed	Failed	Passed	Skipped
9319	5	9314	48

View the top 3 failed test(s) by shortest run time

github.com/steveyegge/gastown/internal/cmd::TestBuildRefineryPatrolVars_FullConfig

Stack Traces | 0s run time

=== RUN   TestBuildRefineryPatrolVars_FullConfig
    patrol_helpers_test.go:166: expected 5 vars, got 7: [target_branch=main integration_branch_refinery_enabled=true integration_branch_auto_land=false run_tests=true delete_merged_branches=true judgment_enabled=false review_depth=standard]
--- FAIL: TestBuildRefineryPatrolVars_FullConfig (0.00s)

github.com/steveyegge/gastown/internal/cmd::TestRunHooksSyncNonClaudeAgent

Stack Traces | 0.01s run time

=== RUN   TestRunHooksSyncNonClaudeAgent
Syncing hooks...
  ✓ mayor/.claude/settings.json (created)
  ✓ deacon/.claude/settings.json (created)
  ✓ myrig/crew/.claude/settings.json (created)
warning: role_agents[crew]=opencode - agent "opencode" binary "opencode" not found in PATH, falling back to default

Synced 3 targets (3 created, 0 updated, 0 unchanged)
    hooks_sync_test.go:366: opencode plugin not created in worktree alice
--- FAIL: TestRunHooksSyncNonClaudeAgent (0.01s)

github.com/steveyegge/gastown/internal/doctor::TestHooksSyncCheck_Fix_TemplateAgent

Stack Traces | 0.01s run time

=== RUN   TestHooksSyncCheck_Fix_TemplateAgent
warning: role_agents[crew]=opencode - agent "opencode" binary "opencode" not found in PATH, falling back to default
    hooks_sync_check_test.go:219: expected StatusWarning before fix, got OK
--- FAIL: TestHooksSyncCheck_Fix_TemplateAgent (0.01s)

github.com/steveyegge/gastown/internal/doctor::TestHooksSyncCheck_TemplateAgent_Missing

Stack Traces | 0.01s run time

=== RUN   TestHooksSyncCheck_TemplateAgent_Missing
warning: role_agents[crew]=opencode - agent "opencode" binary "opencode" not found in PATH, falling back to default
    hooks_sync_check_test.go:193: expected StatusWarning for missing template agent file, got OK: All 3 hook targets in sync
--- FAIL: TestHooksSyncCheck_TemplateAgent_Missing (0.01s)

github.com/steveyegge/gastown/internal/doctor::TestHooksSyncCheck_TemplateAgent_OutOfSync

Stack Traces | 0.02s run time

=== RUN   TestHooksSyncCheck_TemplateAgent_OutOfSync
warning: role_agents[crew]=opencode - agent "opencode" binary "opencode" not found in PATH, falling back to default
    hooks_sync_check_test.go:172: expected StatusWarning for out-of-sync template agent, got OK: All 3 hook targets in sync
--- FAIL: TestHooksSyncCheck_TemplateAgent_OutOfSync (0.02s)

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