feat: Xcode + build toolchain classifier with per-project session grouping

[alecf]

Summary

A single Xcode build spawns a swarm of processes that are completely opaque in memory monitors today: multiple parallel swift-frontend compiler jobs, sourcekit-lsp, lldb-rpc-server, xctest runners, xcodebuild, and CoreSimulator daemons. None of them are associated with each other or with the Xcode project they belong to.

An XcodeClassifier would unify all of these under a single group, labeled by the project being built — giving the same per-session clarity that ClaudeCodeClassifier gives for Claude Code sessions.

Processes to claim

Process	Notes
Xcode	Main app
xcodebuild	CLI builds; use working dir for project label
swift-frontend	Parallel compiler jobs; can be many
sourcekit-lsp	Language server
lldb-rpc-server	Debugger
xctest	Test runner
com.apple.CoreSimulator.*	Simulator daemons
Simulator	iOS/tvOS/watchOS simulator UI
XCTRunner	UI test runner

Value

Developers know Xcode is slow and memory-hungry, but have no visibility into what within Xcode is consuming memory. Seeing "Xcode — MyApp.xcodeproj: 4.2 GB (12 swift-frontend jobs)" is a big step up from Activity Monitor.

Implementation notes

• Root detection: com.apple.dt.Xcode bundle ID for the app; xcodebuild executable name for CLI builds
• Project label: parse -project / -workspace / -scheme args from xcodebuild command line, or use Xcode's working directory
• Descendant collection: same recursive parent-PID walk as ClaudeCodeClassifier
• CoreSimulator daemons: detect by process name prefix; associate with the Xcode session that launched them via responsiblePid
• stableIdentifier: "xcode:<project-path>" for stable trending across builds