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/fluxer_server/.dockerignore

@@ -0,0 +1,57 @@
+!.env.example
+$RECYCLE.BIN/
+*.crt
+*.db
+*.db-journal
+*.key
+*.log
+*.map
+*.pem
+*.spec.ts
+*.spec.tsx
+*.swo
+*.swp
+*.sqlite
+*.test.ts
+*.test.tsx
+*.tmp
+*~
+.AppleDouble
+.DS_Store
+.Trash-*
+.cache/
+.circleci/
+.classpath
+.env
+.env.*
+.git/
+.gitattributes
+.github/
+.gitignore
+.gitlab-ci.yml
+.idea/
+.LSOverride
+.nyc_output/
+.pnpm-store/
+.project
+.settings/
+.travis.yml
+.turbo/
+.vscode/
+__mocks__/
+__tests__/
+build/
+CHANGELOG.md
+CONTRIBUTING.md
+coverage/
+data/
+desktop.ini
+dist/
+docs/
+node_modules/
+out/
+README.md
+secrets/
+temp/
+Thumbs.db
+tmp/