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/deploy_workflow.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+from collections.abc import Mapping, Sequence
+
+from ci_steps import (
+    ADD_KNOWN_HOSTS_SCRIPT,
+    INSTALL_DOCKER_PUSSH_SCRIPT,
+    record_deploy_commit_script,
+    set_build_timestamp_script,
+)
+from ci_workflow import EnvArg, parse_step_env_args
+from ci_utils import Step, run_step
+
+
+def build_standard_deploy_steps(
+    *,
+    push_and_deploy_script: str,
+    include_sentry: bool = False,
+    include_build_timestamp: bool = True,
+) -> dict[str, Step]:
+    steps: dict[str, Step] = {
+        "record_deploy_commit": record_deploy_commit_script(
+            include_env=True,
+            include_sentry=include_sentry,
+        ),
+    }
+    if include_build_timestamp:
+        steps["set_build_timestamp"] = set_build_timestamp_script()
+    steps["install_docker_pussh"] = INSTALL_DOCKER_PUSSH_SCRIPT
+    steps["add_known_hosts"] = ADD_KNOWN_HOSTS_SCRIPT
+    steps["push_and_deploy"] = push_and_deploy_script
+    return steps
+
+
+def run_deploy_workflow(
+    steps: Mapping[str, Step],
+    *,
+    env_args: Sequence[EnvArg] | None = None,
+) -> int:
+    args = parse_step_env_args(env_args, include_server_ip=True)
+    run_step(steps, args.step)
+    return 0