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/Views/Main/ChatView.swift

@@ -123,6 +123,16 @@ struct ChatView: View {
                 onDeny: { MCPService.shared.denyPendingBashCommand() }
             )
         }
+        .sheet(item: Binding(
+            get: { MCPService.shared.pendingPersonalDataAction },
+            set: { _ in }
+        )) { pending in
+            PersonalDataApprovalSheet(
+                pending: pending,
+                onApprove: { forSession in MCPService.shared.approvePendingPersonalDataAction(forSession: forSession) },
+                onDeny: { MCPService.shared.denyPendingPersonalDataAction() }
+            )
+        }
     }
 }