feat(pi): switch provision_database to requestDatabase

[marslavish]

Summary

• provision_database now requests through the requestDatabase mutation on the api endpoint instead of inserting a databaseProvisionModule row; the JWT user owns the database, so ownerId is no longer sent
• new preset-match.ts mirrors the backend's modules_hash semantics (order-insensitive, bare name = empty-options tuple, canonicalized options): a preset-equal module set sends presetSlug (warm-pool eligible), any delta sends explicit modules — never both
• new request-database.ts polls the provision ticket on the modules endpoint (2 s interval, 240 s deadline, 3 consecutive failed polls tolerated, mutation ticket checked before the first sleep) until status and bootstrapStatus are both completed; failures surface errorMessage / bootstrapError
• dropped the blanket withRetry around provisioning; deleted create-database-provision.ts
• stable: module paths and exports (env-file, resolve, pg-fixups, credential, db-probe), tool name/args, ProvisionDatabaseDetails shape, .env write before return, probe/skip/reprovision, pg fixups, prewarm
• 22 new tests (injectable executor + branch selection); README documents the flow and the local jobs-worker requirement