fix(web): surface error when adding a workspace by path fails (#1236)

* fix(web): surface error when adding a workspace by path fails

Previously, addWorkspaceByPath swallowed any error from the daemon and created a local-only workspace that could not host sessions and vanished on reload, so an invalid absolute path appeared to succeed but never took effect. Now the error is reported to the user and no fake workspace is added.

* fix(web): preserve pending prompt when adding workspace fails

addWorkspaceByPath now returns a boolean success signal. handleAddWorkspace only clears pendingWorkspaceSubmit and sends the prompt on success, so a daemon-rejected path no longer drops the user's pending submission; they can retry with a valid path.

* fix(web): keep workspace picker open when add fails

Move closing the add-workspace dialog until after a successful add. On a daemon-rejected path the picker now stays open with the user's input intact, so they can correct the path and retry; the pending submission is consumed by a successful retry or dropped only when the user explicitly closes the picker.

* fix(web): show add-workspace errors inline in the picker

When the daemon rejects a path, the global warning toast rendered behind the picker's backdrop (z-index 60 vs 200) and could auto-dismiss unseen. Surface the failure as an inline error inside the dialog instead, so it is visible and persists until the user retries or closes. addWorkspaceByPath now returns a boolean and leaves surfacing to the caller; the picker shows a localized inline message.

.changeset/fix-web-add-workspace-invalid-path.md

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+"@moonshot-ai/kimi-code": patch
+---
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+Fix adding a workspace by path in the web UI failing silently when the daemon rejects the path; it now shows an error instead of a broken workspace.