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_docs/resources/read_states.mdx

@@ -0,0 +1,17 @@
+---
+title: 'Read states'
+description: 'Read states object schemas from the Fluxer API.'
+---
+
+<a id="readstateackbulkrequest"></a>
+
+## ReadStateAckBulkRequest
+
+**Related endpoints**
+
+- [`POST /read-states/ack-bulk`](/api-reference/read-states/mark-channels-as-read)
+
+| Field | Type | Description |
+|-------|------|-------------|
+| read_states | [DeleteMessageRequest](#deletemessagerequest)[] | Array of channel/message pairs to acknowledge |
+