feat(integrations): add upstash Stripe catalog provider

[snowmead]

Summary

• Adds the upstash 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

Medium Risk
New managed integrations provision real credentials (URLs/tokens); provisional output envelopes could mismatch live Stripe until discover is run.

Overview
Adds Phase 1 Stripe Projects Upstash integrations: qstash, redis, search, and vector as managed CatalogResource adapters (catalog-mapped config, ${integrations.*} outputs, shared provision lifecycle). Each service is registered in register_providers! and covered by catalog gap + hermetic provision_script tests; OUTPUT_FIELDS are provisional until live mise run discover.

SDK: extends stackless-provider-sdk config helpers with int_optional, bool_required, and bool_optional (used e.g. for vector dimension).

Process/docs: introduces docs/PROVIDER-WAVES.md, links it from ADDING-A-PROVIDER.md, and records catalog-first rollout in DECISIONS.md. Adds scripts/generate_catalog_integrations.py to scaffold remaining catalog deployables (Upstash included in its hints/registry generation).

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