Add personal data tools, 2nd Brain trust toggle, and research agents

Personal Data Tools: native Calendar, Reminders, Contacts (hidden pending
Apple TCC fix in beta), and Location & Maps access via EventKit, Contacts
framework, and MapKit. Write actions (create event/reminder, complete
reminder) gate through an approval sheet. Four hardened-runtime entitlements
added to oAI.entitlements; Info.plist usage strings added for all services.
Personal Data section shows a β badge while Contacts is hidden.

2nd Brain always-trust: inline toggle on the Agent Skills row for the skill
named "2nd Brain" skips the bash approval dialog when the command contains
.brain_helper.py, gated by three runtime checks in MCPService.

Research agents: spawn_research_agents tool runs up to 5 concurrent read-only
sub-agents (read_file, list_directory, search_files, web_search — no write,
no bash, no nesting). Bounded by maxConcurrentAgents setting (default 3) and
a hard ceiling of 8 tasks. Added items field to Tool.Function.Parameters.Property
for JSON Schema array support; wired into AnthropicProvider.convertParametersToDict.

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

oAI/Models/AgentSkill.swift

@@ -57,4 +57,10 @@ struct AgentSkill: Codable, Identifiable {
         }
         return name
     }
+
+    /// Matches the user's "2nd Brain" skill by name — there's no canonical skill ID,
+    /// so this is the only way to recognize it (used to gate the "always trust" bash setting).
+    var isSecondBrainSkill: Bool {
+        name.trimmingCharacters(in: .whitespacesAndNewlines).caseInsensitiveCompare("2nd Brain") == .orderedSame
+    }
 }