Add GH Actions build workflow for backend

[tomvothecoder]

Description

Closes #32

This pull request adds a GitHub Actions CI workflow for backend testing and code quality checks, along with configuration updates to support environment-based settings and comprehensive test coverage improvements.

Key Changes:

• Introduces a complete CI/CD workflow with PostgreSQL service, uv dependency management, pre-commit hooks, and pytest
• Updates config.py to conditionally load .env files based on CI environment detection
• Adds/updates tests for 100% backend coverage, including new tests for main app, OAuth flow, and configuration handling
• Adds mypy type checking to pre-commit hooks

Requirements

Build Workflow:

• Postgres setup
• Environment variable setup
• uv environment setup with caching
• Pre-commit hooks with caching
• Pytest

Codebase updates

• Update config.py to support os.env variables and use .env file as a backup
• Fix unit tests
• Add unit tests for 100% coverage of backend

Checklist

• Code follows project style guidelines
• Self-reviewed code
• No new warnings
• Tests added or updated (if needed)
• All tests pass (locally and CI/CD)
• Documentation/comments updated (if needed)
• Breaking change noted (if applicable)

Deployment Notes (if any)

[Copilot]

Pull request overview

This pull request adds a GitHub Actions CI workflow for backend testing and code quality checks, along with configuration updates to support environment-based settings and comprehensive test coverage improvements.

Key Changes:

• Introduces a complete CI/CD workflow with PostgreSQL service, uv dependency management, pre-commit hooks, and pytest
• Updates config.py to conditionally load .env files based on CI environment detection
• Adds/updates tests for 100% backend coverage, including new tests for main app, OAuth flow, and configuration handling
• Adds mypy type checking to pre-commit hooks

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
.github/workflows/build.yml	New CI workflow with PostgreSQL, Python 3.13, uv, pre-commit, and pytest steps
backend/app/core/config.py	Enhanced get_env_file() to detect CI environment and skip .env file requirements
backend/tests/test_main.py	New test file for main app health endpoint and metadata
backend/tests/features/user/test_oauth.py	New comprehensive tests for OAuth cookie transport functionality
backend/tests/features/user/test_api.py	Updated API paths to include /api prefix for auth and user routes
backend/tests/features/simulation/test_schemas.py	Updated status values from "new" to "created" and removed AnyUrl usage
backend/tests/features/simulation/test_api.py	Updated API paths to include /api prefix for simulation routes
backend/tests/features/machine/test_api.py	Updated API paths to include /api prefix for machine routes
backend/tests/core/test_config.py	Added CI environment test and type ignore comments for union-attr
backend/app/scripts/seed.py	Removed redundant type annotation
.pre-commit-config.yaml	Added mypy type checking hook

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