feat(config): add GitHub configuration for setup command

Adds .core/github.yaml with org-standard labels, webhook templates,
branch protection rules, and security settings for use with
`core setup github`.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.core/github.yaml

@@ -0,0 +1,157 @@
+# GitHub repository configuration for Host UK organisation.
+# Used by: core setup github
+#
+# Environment variables can be referenced using ${VAR} or ${VAR:-default} syntax.
+
+version: 1
+
+# Organisation-standard labels
+labels:
+  # Priority labels
+  - name: "priority:critical"
+    color: "b60205"
+    description: "Must be fixed immediately"
+  - name: "priority:high"
+    color: "d93f0b"
+    description: "Should be fixed soon"
+  - name: "priority:medium"
+    color: "fbca04"
+    description: "Normal priority"
+  - name: "priority:low"
+    color: "0e8a16"
+    description: "Nice to have"
+
+  # Type labels
+  - name: "type:bug"
+    color: "d73a4a"
+    description: "Something isn't working"
+  - name: "type:feature"
+    color: "a2eeef"
+    description: "New feature or request"
+  - name: "type:enhancement"
+    color: "84b6eb"
+    description: "Improvement to existing feature"
+  - name: "type:docs"
+    color: "0075ca"
+    description: "Documentation improvements"
+  - name: "type:refactor"
+    color: "d4c5f9"
+    description: "Code refactoring"
+  - name: "type:test"
+    color: "bfd4f2"
+    description: "Test improvements"
+  - name: "type:chore"
+    color: "fef2c0"
+    description: "Maintenance tasks"
+  - name: "type:security"
+    color: "ee0701"
+    description: "Security-related issue"
+
+  # Status labels
+  - name: "status:blocked"
+    color: "b60205"
+    description: "Blocked by another issue or external factor"
+  - name: "status:in-progress"
+    color: "fbca04"
+    description: "Currently being worked on"
+  - name: "status:review"
+    color: "6f42c1"
+    description: "Ready for review"
+  - name: "status:ready"
+    color: "0e8a16"
+    description: "Ready for development"
+
+  # Agent labels (for AI-assisted development)
+  - name: "agent:ready"
+    color: "00ff00"
+    description: "Task ready for AI agent pickup"
+  - name: "agent:assigned"
+    color: "1d76db"
+    description: "Task assigned to AI agent"
+  - name: "agent:blocked"
+    color: "e99695"
+    description: "Agent needs human input"
+  - name: "agent:completed"
+    color: "0e8a16"
+    description: "Agent completed the task"
+
+  # Scope labels
+  - name: "scope:api"
+    color: "c5def5"
+    description: "API changes"
+  - name: "scope:ui"
+    color: "bfdadc"
+    description: "User interface changes"
+  - name: "scope:db"
+    color: "d4c5f9"
+    description: "Database changes"
+  - name: "scope:infra"
+    color: "f9d0c4"
+    description: "Infrastructure changes"
+  - name: "scope:deps"
+    color: "fef2c0"
+    description: "Dependency updates"
+
+  # Workflow labels
+  - name: "breaking"
+    color: "b60205"
+    description: "Contains breaking changes"
+  - name: "good first issue"
+    color: "7057ff"
+    description: "Good for newcomers"
+  - name: "help wanted"
+    color: "008672"
+    description: "Extra attention is needed"
+  - name: "wontfix"
+    color: "ffffff"
+    description: "This will not be worked on"
+  - name: "duplicate"
+    color: "cfd3d7"
+    description: "This issue or pull request already exists"
+
+# Webhooks (optional - set env vars to enable)
+webhooks:
+  discord-push:
+    url: ${DISCORD_WEBHOOK_PUSH:-}
+    events:
+      - push
+      - release
+    content_type: json
+
+  discord-issues:
+    url: ${DISCORD_WEBHOOK_ISSUES:-}
+    events:
+      - issues
+      - issue_comment
+      - pull_request
+      - pull_request_review
+    content_type: json
+
+# Branch protection rules
+branch_protection:
+  - branch: main
+    required_reviews: 1
+    dismiss_stale: true
+    require_code_owner_reviews: false
+    enforce_admins: false
+    require_linear_history: false
+    allow_force_pushes: false
+    allow_deletions: false
+    require_conversation_resolution: true
+
+  - branch: dev
+    required_reviews: 1
+    dismiss_stale: true
+    require_code_owner_reviews: false
+    enforce_admins: false
+    require_linear_history: false
+    allow_force_pushes: false
+    allow_deletions: false
+    require_conversation_resolution: false
+
+# Security settings
+security:
+  dependabot_alerts: true
+  dependabot_security_updates: true
+  secret_scanning: true
+  push_protection: true