Add Arrtrix runtime, config, onboarding, and webhook support

- Implement runtime package for bridge startup, config loading, and env
  overrides
- Add onboarding package for management room welcome messages
- Add matrixcmd package for command processing and help
- Add webhook package with Radarr webhook support and validation
- Extend connector config for webhooks and validation
- Update default config and example config for new options
- Add tests for new packages and config validation
- Change database type default to sqlite3-fk-wal

packages/arrtrix/pkg/runtime/example.go

@@ -0,0 +1,69 @@
+package runtime
+
+import (
+	"fmt"
+	"strings"
+
+	"maunium.net/go/mautrix/bridgev2"
+)
+
+func makeExampleConfig(networkName bridgev2.BridgeName, networkExample string) string {
+	var builder strings.Builder
+
+	builder.WriteString("# Network-specific config options\n")
+	builder.WriteString("network:\n")
+	for _, line := range strings.Split(strings.TrimRight(networkExample, "\n"), "\n") {
+		if line == "" {
+			builder.WriteString("  \n")
+			continue
+		}
+		builder.WriteString("  ")
+		builder.WriteString(line)
+		builder.WriteByte('\n')
+	}
+	builder.WriteByte('\n')
+
+	builder.WriteString(fmt.Sprintf(`bridge:
+  command_prefix: "%s"
+  permissions:
+    "*": relay
+    "@admin:example.com": admin
+
+database:
+  type: sqlite3-fk-wal
+  uri: file:arrtrix.db?_txlock=immediate
+
+homeserver:
+  address: http://example.localhost:8008
+  domain: example.com
+  software: standard
+
+appservice:
+  address: http://localhost:%d
+  hostname: 127.0.0.1
+  port: %d
+  id: %s
+  bot:
+    username: %s
+    displayname: %s
+  as_token: This value is generated when generating the registration
+  hs_token: This value is generated when generating the registration
+  username_template: %s_{{.}}
+
+logging:
+  min_level: info
+  writers:
+    - type: stdout
+      format: pretty-colored
+
+management_room_texts:
+  welcome: ""
+  welcome_connected: ""
+  welcome_unconnected: ""
+  additional_help: ""
+
+env_config_prefix: ""
+`, networkName.DefaultCommandPrefix, networkName.DefaultPort, networkName.DefaultPort, networkName.NetworkID, "arrtrixbot", "Arrtrix Bot", networkName.NetworkID))
+
+	return builder.String()
+}