chore: establish authorship — Holden Salomon

- LICENSE: add copyright line for Holden Salomon (retain original)
- pyproject.toml: update authors to Holden Salomon <holden@arch.fyi>
- README: lead with what the software does rather than fork attribution;
  merge split env var tables into one unified reference; add lint/test
  badges; move attribution to footer

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -4,7 +4,7 @@ version = "0.1.0"
 description = "Immich to Frigate training sets"
 license = "MIT"
 requires-python = ">=3.12"
-authors = [{ name = "sudolulo" }]
+authors = [{ name = "Holden Salomon", email = "holden@arch.fyi" }]
 keywords = ["immich", "frigate", "face-recognition", "training-data", "arcface", "insightface"]
 classifiers = [
     "Development Status :: 3 - Alpha",