feat(integrations): add railway Stripe catalog provider

[snowmead]

Summary

• Adds the railway Stripe Projects catalog integration family as CatalogResource adapter(s).
• Follows docs/ADDING-A-PROVIDER.md and docs/PROVIDER-WAVES.md.
• Includes gap test + hermetic provision test. OUTPUT_FIELDS provisional until mise run discover.

Test plan

• Gap + hermetic tests in module
• Live mise run discover when provider is linked
• Merge after resolving additive registry.rs conflict with other family PRs

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Note

Low Risk
Additive catalog adapters following the existing Cloudflare pattern; no auth or lifecycle engine changes. Provisional output envelopes may need discover before live use.

Overview
Adds Phase 1 Stripe Projects catalog integrations for Railway: railway/bucket, railway/hosting, railway/mongo, railway/postgres, and railway/redis. Each is a managed CatalogResource with catalog gap tests and hermetic provision_script tests; OUTPUT_FIELDS are provisional until mise run discover.

Wires the family into register_providers!, pub mod railway, and extends catalog_outputs_match_output_fields for all five types. stackless-provider-sdk gains shared int_optional, bool_required, and bool_optional config helpers for generated and future adapters.

Also documents catalog-first rollout (PROVIDER-WAVES.md, DECISIONS.md §3) and adds scripts/generate_catalog_integrations.py to scaffold remaining deployables without rewriting registry/mod by hand.

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