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/.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,57 @@
+name: Bug report
+description: Report a reproducible problem in Fluxer
+labels: ['bug']
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for the report.
+
+        Please check our status page at https://fluxerstatus.com and search for existing issues before filing.
+        Security issues should go to https://fluxer.app/security.
+  - type: textarea
+    id: summary
+    attributes:
+      label: Summary
+      description: What happened, and what did you expect instead?
+      placeholder: "When I ..., the app ..., but I expected ..."
+    validations:
+      required: true
+  - type: textarea
+    id: repro
+    attributes:
+      label: Steps to reproduce
+      description: Provide clear, numbered steps.
+      placeholder: |
+        1. Go to ...
+        2. Click ...
+        3. See ...
+    validations:
+      required: true
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment (optional)
+      description: Include versions that matter (commit/tag, OS, runtime, browser/device).
+      placeholder: |
+        - Commit/Tag:
+        - OS:
+        - Runtime:
+        - Browser (if applicable):
+    validations:
+      required: false
+  - type: textarea
+    id: logs
+    attributes:
+      label: Logs or screenshots (optional)
+      description: Paste logs (redact secrets) or attach screenshots/recordings.
+      placeholder: "Paste stack traces, console output, network errors, etc."
+    validations:
+      required: false
+  - type: checkboxes
+    id: checks
+    attributes:
+      label: Checks
+      options:
+        - label: I searched for existing issues and didn't find a duplicate.
+          required: true