feat(sdks): add ts/python/go/libmoltis SDK foundations with CI and docs

[penso]

Summary

• add a new sdks/ workspace with shared GraphQL schema + shared operations
• scaffold first-party SDKs:
  • sdks/typescript (GraphQL Codegen client preset, strict TS, tests)
  • sdks/python (uv + ariadne-codegen + typed async client + tests)
  • sdks/go (genqlient + typed client helpers + tests)
  • sdks/libmoltis packaging docs + build script for XCFramework artifacts
• add schema sync script (scripts/export-graphql-schema.sh) and wire iOS schema export to it
• add new just targets for SDK generate/check/build workflows
• add SDK CI workflow (.github/workflows/sdk-ci.yml) and SDK release workflow (.github/workflows/sdk-release.yml)
• add docs pages for SDK overview and each SDK track, and link SDK docs from README + mdBook summary

Validation

Completed

• ./scripts/export-graphql-schema.sh --check
• cd sdks/typescript && npm run generate && npm run typecheck && npm run test && npm run pack:dry
• cd sdks/go && go mod tidy && go generate ./... && go test ./...
• cd sdks/python && uv sync --group dev && uv run ariadne-codegen && uv run ruff check . && uv run mypy . && uv run pytest

Remaining

• just sdk-libmoltis-build

Manual QA

1. Run just sdk-schema-check and confirm both iOS and SDK schema paths are in sync.
2. Run just sdk-typescript-check, just sdk-python-check, and just sdk-go-check.
3. On macOS, run just sdk-libmoltis-build and verify artifacts in sdks/libmoltis/dist/.
4. Verify docs pages render in mdBook (docs/src/sdks.md + per-SDK pages).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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