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/packages/mime_utils/tsconfig.json

@@ -0,0 +1,9 @@
+{
+	"extends": "../../tsconfigs/base.json",
+	"compilerOptions": {
+		"composite": true,
+		"rootDir": ".",
+		"outDir": "dist"
+	},
+	"include": ["src"]
+}