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/config/src/schema/defs/integrations/clamav.json

@@ -0,0 +1,29 @@
+{
+	"clamav_integration": {
+		"type": "object",
+		"description": "ClamAV antivirus integration.",
+		"additionalProperties": false,
+		"properties": {
+			"enabled": {
+				"type": "boolean",
+				"default": false,
+				"description": "Enable ClamAV scanning."
+			},
+			"host": {
+				"type": "string",
+				"default": "clamav",
+				"description": "ClamAV host."
+			},
+			"port": {
+				"type": "number",
+				"default": 3310,
+				"description": "ClamAV port."
+			},
+			"fail_open": {
+				"type": "boolean",
+				"default": true,
+				"description": "If true, allow files if scanning fails."
+			}
+		}
+	}
+}