chore: use Pydantic to generate OpenAPI schema

Removes the need for the strong_typing and pyopenapi packages and purely
use Pydantic for schema generation.

Signed-off-by: Sébastien Han <seb@redhat.com>

.pre-commit-config.yaml

@@ -42,7 +42,6 @@ repos:
     hooks:
     -   id: ruff
         args: [ --fix ]
-        exclude: ^src/llama_stack/strong_typing/.*$
     -   id: ruff-format
 
 -   repo: https://github.com/adamchainz/blacken-docs
@@ -111,11 +110,11 @@ repos:
         name: API Spec Codegen
         additional_dependencies:
           - uv==0.7.8
-        entry: sh -c './scripts/uv-run-with-index.sh run ./docs/openapi_generator/run_openapi_generator.sh > /dev/null'
+        entry: sh -c './scripts/uv-run-with-index.sh run scripts/fastapi_generator.py docs/static'
         language: python
         pass_filenames: false
         require_serial: true
-        files: ^src/llama_stack/apis/|^docs/openapi_generator/
+        files: ^src/llama_stack/apis/
       - id: check-workflows-use-hashes
         name: Check GitHub Actions use SHA-pinned actions
         entry: ./scripts/check-workflows-use-hashes.sh