[GaganSD]

• Replaces TypeBox schemas and validation with @earendil-works/pi-schema across search + output schemas and tests.
• Adds @earendil-works/pi-schema@1.5.0 as the single runtime dependency (zero transitive deps); removes the typebox peer and dev dependency.
• Keeps schema JSON equivalent: open/closed objects preserved, string enums keep type: "string", and only lit() loses the redundant type key.
• Updates package-content guards to validate the schema dependency and reject any additional runtime dependency.
• Verified with lint, typecheck, unit tests, integration tests, artifact build/smoke, schema snapshot comparison, and a clean npm ci.