fix(auth): make plan and org fetches non-fatal, always persist auth

[ManthanNimodiya]

Summary

Even after the org-fetch fix in #1896, auth still didn't persist on self-hosted because organizations_updated_at was never stamped when fetches failed, and hasCompleteOrganizationCache requires it to be set for signedIn() to return true.

Both plan and org fetches are now non-fatal. Whatever succeeds gets saved, and organizations_updated_at is always stamped at the end, so the UI sees a valid cache and stays signed in regardless of what the self-hosted server returns.

Confirmed working against https://demos.alphaomegateam.co/

Greptile Summary

This PR makes the /api/desktop/plan and /api/desktop/organizations fetches non-fatal inside update_auth_plan, and ensures Self::set is always called so auth is persisted regardless of which fetches succeed or fail. The fix specifically targets self-hosted deployments where these endpoints may not exist.

• Plan fetch now uses a match block with tracing::warn! on any failure or non-success status, and only updates auth.plan on a valid 200 + parseable JSON response.
• Org fetch failure now stamps organizations_updated_at when auth.organizations is empty, which is the key unlock for signedIn() to return true on self-hosted (where the org endpoint returns 404 and no prior cache exists).
• The is_empty() guard on the error branch is a targeted improvement over unconditionally stamping the timestamp, but the cloud-vs-self-hosted ambiguity on a first login (empty cached orgs + transient failure) remains an open concern per the existing review thread.

Confidence Score: 4/5

Safe to merge for self-hosted scenarios; the unresolved ambiguity around empty-org stamping on first login still applies to cloud deployments with transient failures.

The auth persistence logic is now correct for the self-hosted case. The is_empty() guard on the error branch reduces the blast radius compared to unconditional stamping, but on a first login against a cloud server where the org endpoint transiently returns an error, organizations_updated_at will still be stamped with an empty org list, leaving the UI in a signed-in-but-no-orgs state. No new functional regressions were introduced beyond what was already flagged in the prior review thread.

apps/desktop/src-tauri/src/auth.rs — specifically the error branch of the org fetch (lines 103–108) and the interaction with the frontend's hasCompleteOrganizationCache freshness check.

Important Files Changed

Filename	Overview
apps/desktop/src-tauri/src/auth.rs	Plan and org fetches made non-fatal; auth is now always persisted via unconditional Self::set; organizations_updated_at is stamped on success or on failure when auth.organizations is empty, with the previous reviewer concern partially addressed by the is_empty() guard.

_{Reviews (2): Last reviewed commit: "fix(auth): only stamp org timestamp on f..." | Re-trigger Greptile}

[ManthanNimodiya]

@greptileai please re-review