Implement PyPI release workflow

[slusset]

Summary

• add a release workflow that validates tag/version alignment, builds both sdist and wheel artifacts, publishes via PyPI trusted publishing, and verifies installability
• trigger release publishing from GitHub releases and version tags while skipping duplicate publishes for versions already on PyPI
• add a PyPI badge and install/publish guidance to the README

Verification

• uv run pytest tests/unit -v --tb=short
• uv run ruff check src/ tests/
• uv run ruff format --check src/ tests/
• uv run mypy src/ehr_writeback/core/
• uv build

Notes

• src/ehr_writeback/pipelines/writeback_pipeline.py:10: error: Cannot find implementation or library stub for module named "dlt" [import-not-found]
  src/ehr_writeback/pipelines/writeback_pipeline.py:11: error: Cannot find implementation or library stub for module named "pyspark.sql" [import-not-found]
  src/ehr_writeback/pipelines/writeback_pipeline.py:16: error: Name "spark" is not defined [name-defined]
  src/ehr_writeback/pipelines/writeback_pipeline.py:17: error: Name "spark" is not defined [name-defined]
  src/ehr_writeback/pipelines/writeback_pipeline.py:26: error: Function is missing a return type annotation [no-untyped-def]
  src/ehr_writeback/pipelines/writeback_pipeline.py:28: error: Name "spark" is not defined [name-defined]
  src/ehr_writeback/pipelines/writeback_pipeline.py:40: error: Function is missing a return type annotation [no-untyped-def]
  src/ehr_writeback/infrastructure/delta_store.py:13: error: Cannot find implementation or library stub for module named "pyspark.sql" [import-not-found]
  src/ehr_writeback/infrastructure/delta_store.py:13: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
  src/ehr_writeback/infrastructure/idempotency.py:34: error: Returning Any from function declared to return "bool" [no-any-return]
  src/ehr_writeback/infrastructure/idempotency.py:53: error: Cannot find implementation or library stub for module named "delta.tables" [import-not-found]
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:14: error: Name "dbutils" is not defined [name-defined]
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:22: error: Name "dbutils" is not defined [name-defined]
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:26: error: Name "dbutils" is not defined [name-defined]
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:31: error: Name "spark" is not defined [name-defined]
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:42: error: Function is missing a return type annotation [no-untyped-def]
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:42: note: Use "-> None" if function does not return a value
  src/ehr_writeback/pipelines/reprocess_dead_letters.py:54: error: Call to untyped function "reprocess" in typed context [no-untyped-call]
  src/ehr_writeback/adapters/generic/smart_auth.py:44: error: Argument 2 has incompatible type "DHPrivateKey | Ed25519PrivateKey | Ed448PrivateKey | RSAPrivateKey | DSAPrivateKey | EllipticCurvePrivateKey | X25519PrivateKey | X448PrivateKey"; expected "RSAPrivateKey | EllipticCurvePrivateKey | Ed25519PrivateKey | Ed448PrivateKey | PyJWK | str | bytes" [arg-type]
  src/ehr_writeback/adapters/generic/fhir_r4_adapter.py:30: error: Missing type parameters for generic type "dict" [type-arg]
  src/ehr_writeback/adapters/generic/fhir_r4_adapter.py:31: error: Missing type parameters for generic type "dict" [type-arg]
  src/ehr_writeback/adapters/epic/auth.py:48: error: Argument 2 has incompatible type "DHPrivateKey | Ed25519PrivateKey | Ed448PrivateKey | RSAPrivateKey | DSAPrivateKey | EllipticCurvePrivateKey | X25519PrivateKey | X448PrivateKey"; expected "RSAPrivateKey | EllipticCurvePrivateKey | Ed25519PrivateKey | Ed448PrivateKey | PyJWK | str | bytes" [arg-type]
  src/ehr_writeback/adapters/epic/flowsheet_adapter.py:34: error: Missing type parameters for generic type "dict" [type-arg]
  src/ehr_writeback/adapters/epic/fhir_adapter.py:27: error: Missing type parameters for generic type "dict" [type-arg]
  src/ehr_writeback/adapters/epic/fhir_adapter.py:29: error: Missing type parameters for generic type "dict" [type-arg]
  src/ehr_writeback/adapters/cerner/fhir_adapter.py:33: error: Missing type parameters for generic type "dict" [type-arg]
  src/ehr_writeback/adapters/cerner/fhir_adapter.py:34: error: Missing type parameters for generic type "dict" [type-arg]
  Found 25 errors in 10 files (checked 24 source files) still reports pre-existing issues in Databricks and adapter modules outside this change scope