Validate boolean tokens for wrapped _default_on kill-switch readers #24120

The cross-service reader inventory now recognizes _default_on(<ENV constant>), but the resulting EnvRead has no truthy tokens. check_boolean_tokens therefore skips this reader shape.

In legacy capture-coverage mode, the live-STT helper treats any value outside false/0/off as true. A future typo such as flase could pass the deployment checker and leave a supposedly disabled switch on. The prod replica-recovery declaration in PR #24118 is the valid literal false; this finding does not invalidate that configuration.

Teach the checker the wrapper's boolean grammar and cover both accepted literals and invalid tokens, while preserving rejection of unread ops kill switches. Keep serving behavior unchanged unless separately approved.

Source:

Found by the read-only Luna delta review of #24118 (P2, overall SHIP). Coordination owner: rollout lead; target review/assignment by 2026-11-06. Tracked under the Margin-50 initiative in ANX. Evidence report: data/run-2026-10-13-two-lane-nemotron/swarm/state/refs/routerfix-report-2026-10-30.md in omi-workspace.