Improve README and restore CI

[shaypal5]

Summary

• Replaces the empty README with a polished homepage-style introduction for Furever Match.
• Adds a GitHub Actions CI workflow using uv and Python 3.12.
• Declares missing runtime and dev dependencies so clean environments can install and run tests.
• Fixes test discovery, the broken Flask smoke test, and pytest warnings in the matching demo tests.
• Makes Supabase client creation lazy so import-only/unit-test paths do not require database secrets.

Why

The repository had no meaningful README and no GitHub Actions runs. A clean local test run also failed because pytest was not declared, pytest configuration used the wrong ini section, and importing app modules eagerly required Supabase credentials. These changes make the project more inviting for readers and give contributors a working CI baseline.

Impact

• README is intentionally an intro/homepage rather than full project documentation.
• Database-backed routes still require SUPABASE_URL and SUPABASE_KEY at runtime.
• Matching logic behavior was not changed; stale demo wording was updated to reflect the current hard-filter implementation.

Validation

• uv sync --extra dev
• uv run python -m pytest -> 4 passed

Milestone

No milestone assigned: this repository currently has no GitHub milestones.