Switch projects from New Workspace with ⌘P/Ctrl+P (#2110)

* feat(app): add ⌘P shortcut to switch project on New Workspace screen

Opens the existing project picker with its search focused so the project
can be switched from the keyboard (type + Enter) instead of clicking the
badge and then the project.

Wires a new "workspace.project.pick" action through the standard keyboard
pipeline (binding -> route passthrough -> dispatcher), handled by a
screen-scoped handler on the New Workspace screen that is only registered
while the screen is mounted and there are projects to pick. Because
preventDefault only fires when a handler handles the key, ⌘P/Ctrl+P still
triggers native print everywhere else. Adds a Settings -> Shortcuts help
row (rebindable) and the "Switch project" label across all locales.

* test(app): cover project picker shortcut

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/keyboard/route-shortcut.test.ts

@@ -30,6 +30,7 @@ describe("routeKeyboardShortcut — dispatch passthroughs", () => {
     ["agent.interrupt", { id: "agent.interrupt", scope: "global" }],
     ["workspace.tab.new", { id: "workspace.tab.new", scope: "workspace" }],
     ["workspace.new", { id: "workspace.new", scope: "sidebar" }],
+    ["workspace.project.pick", { id: "workspace.project.pick", scope: "workspace" }],
     ["workspace.archive", { id: "workspace.archive", scope: "sidebar" }],
     ["workspace.pin", { id: "workspace.pin", scope: "sidebar" }],
     ["worktree.new", { id: "worktree.new", scope: "sidebar" }],