ci: add GitHub Actions test pipeline

[arashmad]

Summary

Adds a GitHub Actions CI workflow for GeoInsight API.

The workflow runs on pull requests targeting main and pushes to main. It starts a disposable PostGIS database, installs dependencies with uv, applies Alembic migrations, checks migration consistency, runs Ruff checks, and runs the test suite.

Changes

• Added .github/workflows/ci.yml
• Uses Python 3.12
• Installs dependencies with uv sync --dev
• Starts a disposable PostGIS service container
• Sets database environment variables for CI
• Runs uv run alembic upgrade head
• Runs uv run alembic check
• Runs uv run ruff format --check .
• Runs uv run ruff check .
• Runs uv run pytest

Out of scope

• Neon remote database setup
• Deployment pipeline
• Docker image publishing
• Production database setup
• Test coverage thresholds
• Matrix testing

Notes

This CI workflow intentionally uses a disposable PostGIS service container instead of Neon. Regular PR checks should be isolated, reproducible, and independent from external database services.

How tested locally

• uv run alembic upgrade head
• uv run alembic check
• uv run ruff format --check .
• uv run ruff check .
• uv run pytest

Closes #40

[arashmad]

@codex review this pls

[chatgpt-codex-connector]

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