feat: add fluxer upstream source and self-hosting documentation

- Clone of github.com/fluxerapp/fluxer (official upstream)
- SELF_HOSTING.md: full VM rebuild procedure, architecture overview,
  service reference, step-by-step setup, troubleshooting, seattle reference
- dev/.env.example: all env vars with secrets redacted and generation instructions
- dev/livekit.yaml: LiveKit config template with placeholder keys
- fluxer-seattle/: existing seattle deployment setup scripts

fluxer/scripts/ci/pyproject.toml

@@ -0,0 +1,18 @@
+[project]
+name = "fluxer_ci"
+version = "0.0.0"
+requires-python = ">=3.12"
+dependencies = []
+
+[dependency-groups]
+dev = [
+  "pytest==8.3.4",
+]
+
+[tool.pytest.ini_options]
+testpaths = [
+  "tests",
+]
+pythonpath = [
+  ".",
+]