feat: add community infrastructure and update server setup

- releases/manifest.json: Seed release manifest for update server
- update.rs: Make UPDATE_MANIFEST_URL configurable via ARCHIPELAGO_UPDATE_URL env var
- CONTRIBUTING.md: Comprehensive contribution guidelines covering code style,
  PR process, testing, security disclosure, and app submission
- .github/ISSUE_TEMPLATE/: Bug report, feature request, and app submission
  issue templates with structured forms
- .github/pull_request_template.md: PR template with checklist

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -0,0 +1,81 @@
+name: Bug Report
+description: Report a bug in Archipelago
+title: "[Bug]: "
+labels: ["bug", "triage"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thank you for reporting a bug. Please fill out the sections below.
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: A clear description of the bug.
+      placeholder: What happened?
+    validations:
+      required: true
+
+  - type: textarea
+    id: steps
+    attributes:
+      label: Steps to Reproduce
+      description: Minimal steps to reproduce the issue.
+      placeholder: |
+        1. Go to '...'
+        2. Click on '...'
+        3. See error
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected
+    attributes:
+      label: Expected Behavior
+      description: What should have happened?
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual
+    attributes:
+      label: Actual Behavior
+      description: What actually happened?
+    validations:
+      required: true
+
+  - type: input
+    id: version
+    attributes:
+      label: Archipelago Version
+      description: Check Settings page or run `archipelago --version`
+      placeholder: "0.1.0"
+    validations:
+      required: true
+
+  - type: dropdown
+    id: hardware
+    attributes:
+      label: Hardware
+      options:
+        - x86_64 (Intel/AMD)
+        - ARM64 (Raspberry Pi 5)
+        - ARM64 (Other)
+        - Other
+    validations:
+      required: true
+
+  - type: textarea
+    id: logs
+    attributes:
+      label: Relevant Logs
+      description: |
+        Run `journalctl -u archipelago --since "1 hour ago"` and paste relevant output.
+      render: shell
+
+  - type: textarea
+    id: screenshots
+    attributes:
+      label: Screenshots
+      description: If applicable, add screenshots.