chore: delete dead code and the unread managed policy keys

[datlechin]

Stacked on #3376.

Why

Code with no reader in the app, verified against TablePro/, Packages/, Plugins/, TableProMobile/ and the tests.

Change

• Delete OllamaDetector (no caller) and MCPStdioMessageTransport with its tests (not compiled into the mcp-server helper, no caller). RecordingBridgeLogger, which lived in those tests, moves to TableProTests/Core/MCP/Helpers/ for the bridge suites that still use it.
• Delete SyncCoordinator.handleRemoteNotification() and the notification pull behind it: the Mac app never registers for remote notifications, so the deferral flags, the pull task and its test were unreachable.
• Delete TableLoadHistoryStore.records() and exportJSON() and the export tests. The retention and corruption tests now append through the store and read the file back.
• Delete the mcpServerDisabled, aiAssistantDisabled and pluginInstallDisabled managed policy keys, plus bool(_:) and isManaged(_:), which only those keys or tests read. minimumSafeModeLevel stays.

Verified

The touched suites and the bridge suites pass. No user-visible change: none of the removed keys was ever read.

Not in this PR

• No overlap with fix(mcp): refuse every server start while MCP is off #3368, fix(mcp): make approval prompts Return-safe and stop stealing focus #3370, refactor(mcp)!: remove unauthenticated MCP access #3371 or refactor(mcp): ship the tablepro shim in the app bundle #3372; none of them touches these files or symbols.