Fix rig config display and polecat Claude settings validation

[vernon99]

Summary

• include rig-root default_branch in rig config resolution and display
• accept polecat stop hooks in the Claude settings doctor check
• add regression tests for config lookup and Claude settings validation
• update the compact report test for the current helper signature

Verification

• go test ./internal/rig -run 'TestGetConfig_(SystemDefaults|RigRootDefaultBranch)$' -count=1\n- go test ./internal/cmd -run 'Test(GetConfigKeys_IncludesRigDefaultBranch|WispTypeToCategory)$' -count=1\n- go test ./internal/doctor -run 'TestClaudeSettingsCheck_(PolecatStopHookAccepted|MissingStopHook)$' -count=1