Switch Claude execution from services to ephemeral exec sessions

[mcintyre94]

Summary

• Replaces the service-based Claude execution model (PUT /services/{name}) with ephemeral exec WebSocket sessions. Services restart automatically on sprite wake, causing Claude to re-execute old prompts and burn tokens; exec sessions do not restart.
• Exec sessions persist on the server for max_run_after_disconnect=3600s, allowing the app to reattach after backgrounding. If the session has expired (sprite slept), falls back to restoring history from Claude's .jsonl session file on the sprite.
• Splits ExecEvent.data into .stdout / .stderr to prevent heartbeat noise from corrupting the NDJSON parser.
• Adds one-time migration to clean up leftover wisp-claude-* and wisp-quick-* services on existing sprites (gated on currentServiceName != nil so it's a no-op after first run).

Changes

• ExecSession — split .data(Data) into .stdout(Data) / .stderr(Data)
• SpriteChat — add execSessionId: String? for WebSocket reattach
• SpritesAPIClient — remove service streaming methods; add killExecSession, cleanupLegacyServices
• ChatViewModel — replace processServiceStream / runReconnectLoop with processExecStream / reattachToExec / restoreFromSessionFile; fix session restore to trigger on both .timedOut and .disconnected results
• ChatViewModelTests — replace MockServiceLogsProvider with makeExecStream helper; update reconnect tests

Test plan

• Send a message → exec session created, Claude runs, response streams in
• Background app mid-response → reopen → reattaches to running exec, scrollback shown without duplication
• Let sprite sleep after a completed session → reopen → history restored from session file
• Send new message after restore → Claude resumes with --resume {sessionId}
• Interrupt mid-response → new message → fresh Claude session (old process killed)
• First launch on existing install → legacy wisp-claude-* / wisp-quick-* services cleaned up

🤖 Generated with Claude Code

[claude]

Code review

1 issue found.

Compilation error: StreamResult does not conform to Equatable

File: WispTests/ChatViewModelTests.swift, in the new test reattachToExec_setsLastSessionCompleteWhenResultReceived

The test uses #expect(result == .completed) where result is of type StreamResult. StreamResult is declared as enum StreamResult: CustomStringConvertible with no Equatable conformance, so the == operator is not synthesized and this will fail to compile. All other tests in this file correctly use pattern matching instead.

Fix Option A: Add Equatable to the StreamResult declaration in ChatViewModel.swift:
enum StreamResult: Equatable, CustomStringConvertible

Fix Option B: Change the assertion to pattern matching (consistent with the rest of the test suite):
guard case .completed = result else {
Issue.record(message)
return
}