feat: broadcast notification target + UX improvements

Add broadcast target type that fans out notifications to multiple
child targets. Dispatch expands broadcast into children in
load_link_data() — dispatcher stays unaware. Children can be
toggled on/off via disabled_child_ids in config.

Also: dashboard provider card smaller font for names, scroll-to-form
on target edit, broadcast nav tab with counter, flag_modified fix
for JSON column updates, CLAUDE.md nav tree docs.

frontend/src/lib/i18n/en.json

@@ -34,6 +34,7 @@
 		"targetSlack": "Slack",
 		"targetNtfy": "ntfy",
 		"targetMatrix": "Matrix",
+		"targetBroadcast": "Broadcast",
 		"automation": "Automation",
 		"actions": "Actions"
 	},
@@ -256,6 +257,11 @@
 		"descSlack": "Slack channel webhooks for notifications",
 		"descNtfy": "ntfy push notification topics",
 		"descMatrix": "Matrix room destinations for notifications",
+		"descBroadcast": "Send to multiple targets at once",
+		"childTargets": "target(s)",
+		"selectChildTargets": "Select child targets",
+		"noChildTargets": "No child targets configured.",
+		"noChildTargetsAvailable": "Create other targets first, then add them here.",
 		"addTarget": "Add Target",
 		"cancel": "Cancel",
 		"type": "Type",
@@ -814,6 +820,8 @@
 		"syntaxError": "Syntax error",
 		"undefinedVar": "Unknown variable",
 		"line": "line",
+		"enable": "Enable",
+		"disable": "Disable",
 		"add": "Add",
 		"filterByName": "Filter by name...",
 		"allTypes": "All types",