Add streaming log viewer with service switching and filtering (step 6)

ddev logs -f runs indefinitely rather than completing, so it doesn't
fit runStreamed's resolve/reject-on-exit model or the terminal panel's
operation semantics — added a parallel startLogStream/logs:data path
in commandRunner.ts that shares the same process-tracking map (so
stopping a log stream reuses the existing terminal:cancel IPC) but
pushes chunks over a dedicated channel decoupled from the status
bar/toast system. Kill all tracked processes on app quit so a
forgotten open log viewer doesn't leave an orphaned `ddev logs -f`.

Two real bugs found and fixed via live testing:
- react-hooks/set-state-in-effect flagged synchronous setState calls
  used only to reset state on service change. Fixed by keying the
  streaming component by service (LogPane key={service}) so switching
  services remounts it and state resets via useState initializers
  instead — the React-recommended pattern for this.
- Filtering operated on raw stream chunks, not lines: a single data
  chunk can bundle many log lines or split one across chunk
  boundaries, so filtering by chunk let unrelated lines through
  whenever a match happened to share a chunk. Fixed by buffering
  partial lines per stream and only filtering/rendering once complete
  lines are assembled.

Verified end-to-end against the real scratch project via CDP-driven
clicks: live streaming from real containers (db and web service logs
both confirmed with distinct real content), service switching,
filtering (confirmed both the false-positive case is fixed and real
matches still work), and confirmed closing the viewer actually kills
the underlying `ddev logs -f` process rather than leaving it orphaned.

src/preload/index.ts

@@ -6,6 +6,8 @@ import type {
   DdevProjectDetail,
   DdevProjectSummary,
   DdevSnapshot,
+  LogDataEvent,
+  LogExitEvent,
   TerminalDataEvent,
   TerminalExitEvent
 } from '../shared/types'
@@ -63,6 +65,20 @@ const api = {
       ipcRenderer.invoke('addons:install', operationId, name, addonRepo),
     remove: (operationId: string, name: string, addonName: string): Promise<void> =>
       ipcRenderer.invoke('addons:remove', operationId, name, addonName)
+  },
+  logs: {
+    start: (operationId: string, name: string, service: string): Promise<void> =>
+      ipcRenderer.invoke('logs:start', operationId, name, service),
+    onData: (callback: (event: LogDataEvent) => void): (() => void) => {
+      const listener = (_event: IpcRendererEvent, data: LogDataEvent): void => callback(data)
+      ipcRenderer.on('logs:data', listener)
+      return () => ipcRenderer.removeListener('logs:data', listener)
+    },
+    onExit: (callback: (event: LogExitEvent) => void): (() => void) => {
+      const listener = (_event: IpcRendererEvent, data: LogExitEvent): void => callback(data)
+      ipcRenderer.on('logs:exit', listener)
+      return () => ipcRenderer.removeListener('logs:exit', listener)
+    }
   }
 }