feat(backend): add prisma types stub generator for pyright compatibility (#11736)

Prisma's generated `types.py` file is 57,000+ lines with complex
recursive TypedDict definitions that exhaust Pyright's type inference
budget. This causes random type errors and makes the type checker
unreliable.

### Changes 🏗️

- Add `gen_prisma_types_stub.py` script that generates a lightweight
`.pyi` stub file
- The stub preserves safe types (Literal, TypeVar) while collapsing
complex TypedDicts to `dict[str, Any]`
- Integrate stub generation into all workflows that run `prisma
generate`:
  - `platform-backend-ci.yml`
  - `claude.yml`
  - `claude-dependabot.yml`
  - `copilot-setup-steps.yml`
  - `docker-compose.platform.yml`
  - `Dockerfile`
  - `Makefile` (migrate & reset-db targets)
  - `linter.py` (lint & format commands)
- Add `gen-prisma-stub` poetry script entry
- Fix two pre-existing type errors that were previously masked:
- `store/db.py`: Replace private type
`_StoreListingVersion_version_OrderByInput` with dict literal
  - `airtable/_webhook.py`: Add cast for `Serializable` type

### Checklist 📋

#### For code changes:
- [x] I have clearly listed my changes in the PR description
- [x] I have made a test plan
- [x] I have tested my changes according to the test plan:
  - [x] Run `poetry run format` - passes with 0 errors (down from 57+)
  - [x] Run `poetry run lint` - passes with 0 errors
  - [x] Run `poetry run gen-prisma-stub` - generates stub successfully
- [x] Verify stub file is created at correct location with proper
content

#### For configuration changes:
- [x] `.env.default` is updated or already compatible with my changes
- [x] `docker-compose.yml` is updated or already compatible with my
changes
- [x] I have included a list of my configuration changes in the PR
description (under **Changes**)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Chores**
* Added a lightweight Prisma type-stub generator and integrated it into
build, lint, CI/CD, and container workflows.
* Build, migration, formatting, and lint steps now generate these stubs
to improve type-checking performance and reduce overhead during builds
and deployments.
  * Exposed a project command to run stub generation manually.

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settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->