feat(web): add workspace-wide project chat dock (#259)

- Add one project chat dock to every workspace page, with a project
  picker and a separate draft per project.
- Load the projects list only when the dock first opens; fall back to
  the Assistant links outside the workspace dock instead of throwing.
- Keep the dock open across pages; collapse only for focus that follows
  a Tab into controls the panel hides.
- Add a phone scrim and bottom sheet, keep focus inside it, and reserve
  scroll space on desktop (skipped on short screens).
- Cap mounted chat sessions at 3 without dropping drafts or running
  chats; count an unconfirmed project draft as unsent.
- Share one set of planner prefs, AI capabilities and agent settings
  reads across all embedded chats.

Author: luannn010

.gitignore

@@ -28,3 +28,6 @@ backups/
 
 # Downloaded source and research references remain local-only.
 /orbyn-references/
+
+# Local collaboration handoffs.
+.collab/tasks/

web/src/app/workspace/Chrome.tsx

@@ -7,6 +7,7 @@ import {
 } from "../../lib/route-scope";
 import { Shell } from "../Shell";
 import { WorkspaceController } from "./controller";
+import { WorkspaceProjectChat } from "./ProjectChat";
 const inactive = {
   pathname: "/app",
   search: "",
@@ -88,7 +89,9 @@ export function WorkspaceChrome({
       controller={controller}
       origin={working?.lease}
     >
-      {children}
+      <WorkspaceProjectChat controller={controller}>
+        {children}
+      </WorkspaceProjectChat>
     </Shell>
   );
   // A closed/missing dock origin must never silently reroute an action to primary.