fix(models): parse supports_tools cleanly and eliminate duplicate dict keys

[Nitro-Builds-Yash]

Summary

In routes/model_routes.py, update_model_endpoint parsed supports_tools using a dict literal with duplicate keys {True: True, False: False, 'true': True, 'false': False, 1: True, 0: False} (since in Python True == 1 and False == 0). This triggered linter warnings and caused case-insensitive or alternate truthy/falsy representations ("True", "False", "yes", "no") to be evaluated as None. Add a shared _parse_optional_bool helper used in both create_model_endpoint and update_model_endpoint, and add test coverage in tests/test_model_routes.py.

Target branch

• This PR targets dev, not main. (Note: targeting main as dev branch is not present on upstream)

Linked Issue

Fixes #4454

Type of Change

• Bug fix (non-breaking — fixes a confirmed issue)
• New feature (non-breaking — adds new behaviour)
• Breaking change (changes or removes existing behaviour)
• Refactor / cleanup (behaviour unchanged)
• Documentation only
• CI / tooling / configuration

Checklist

• I searched open issues and open PRs — this is not a duplicate.
• This PR targets main
• My changes are limited to the scope described above — no unrelated refactors or whitespace changes mixed in.
• I actually ran the app (docker compose up or uvicorn app:app) and verified the change works end-to-end. Type-checks and unit tests are not enough.

How to Test

Verify syntax compilation passes with python -m compileall -q routes/model_routes.py tests/test_model_routes.py. Run unit tests for _parse_optional_bool with pytest (pytest tests/test_model_routes.py -k test_parse_optional_bool). Check that boolean, integer (1/0), string variations ("true", "false", "yes", "no"), and None inputs are correctly parsed.