feat(sidecars): add proxied sidecar tabs (#279)

## Summary
- add SideCar support across the server and UI, including proxied tabs,
picker/settings flows, and websocket-aware proxying
- unify top-level tab handling so workspace instances and SideCars share
the same tab model and navigation flows
- limit SideCars to port-based services only, removing server-managed
process control from the final API and UI

---------

Co-authored-by: Shantur <shantur@Mac.home>
Co-authored-by: Shantur <shantur@Shanturs-MacBook-Pro-M5.local>

packages/server/src/events/bus.ts

@@ -24,6 +24,8 @@ export class EventBus extends EventEmitter {
     this.on("workspace.error", handler)
     this.on("workspace.stopped", handler)
     this.on("workspace.log", handler)
+    this.on("sidecar.updated", handler)
+    this.on("sidecar.removed", handler)
     this.on("storage.configChanged", handler)
     this.on("storage.stateChanged", handler)
     this.on("instance.dataChanged", handler)
@@ -35,6 +37,8 @@ export class EventBus extends EventEmitter {
       this.off("workspace.error", handler)
       this.off("workspace.stopped", handler)
       this.off("workspace.log", handler)
+      this.off("sidecar.updated", handler)
+      this.off("sidecar.removed", handler)
       this.off("storage.configChanged", handler)
       this.off("storage.stateChanged", handler)
       this.off("instance.dataChanged", handler)