feat: add Docker support and inbound webhooks (Tier 2)

- Dockerfile: multi-stage build (node:22-alpine), better-sqlite3 native deps handled
- .dockerignore + docker-compose.yml for deployment
- FLYNN_DATA_DIR env var support in daemon, CLI, and TUI
- WebhookHandler: ChannelAdapter for HTTP POST /webhooks/:name
- Per-webhook HMAC auth, template rendering ({{body}}, {{json.field}})
- Config schema: automation.webhooks array with name/secret/message/output
- Gateway routes webhook requests before static files (bypasses gateway auth)
- 23 new tests for webhook functionality, 874 total tests passing

.dockerignore

@@ -0,0 +1,35 @@
+node_modules
+dist
+.git
+.gitignore
+.worktrees
+
+# Logs
+*.log
+
+# Environment files
+.env
+.env.*
+!.env.example
+
+# Documentation (keep README)
+docs/
+*.md
+!README.md
+!SOUL.md
+
+# Test files
+src/**/*.test.ts
+vitest.config.*
+
+# Lint config
+eslint.config.*
+
+# Editor / IDE
+.vscode
+.idea
+*.swp
+*.swo
+
+# Claude config
+.claude