fix(frontend): update Purchaser group migration comment from 000058 to 000059

[cristim]

Context

PR LeanerCloud/cloud-commitments-cli#947 renumbered the Purchaser group migration from 000058 to 000059 to avoid a collision.
The backend (internal/auth/types.go:320) and the SQL files were updated, but two frontend
comment references were not:

• frontend/src/permissions.ts:81 -- JSDoc for PURCHASER_GROUP_ID still says migration 000058
• frontend/src/users/userActions.ts:101 -- inline comment still says migration 000058

These are comment-only changes and carry no runtime risk, but they create a misleading paper trail
for future developers reading the code.

Fix

In each file, replace 000058 with 000059 in the migration-reference comment only.

Discovered in

CodeRabbit review of PR LeanerCloud/cloud-commitments-cli#947 (anchored to internal/auth/types.go:320). The files were not in
scope for that PR so the fix was deferred here per scope-discipline rules.

[cristim]

Verification sweep against main (101f099fb) on 2026-07-27 finds the premise of this issue no longer exists on main.
The migration in question was renumbered again after this issue was filed: permissions.ts now correctly references migration 000064, not 000058 or 000059. Implementing the 058->059 change as originally written would encode a wrong value.
Evidence: commit 2d3f0327f (PR LeanerCloud/cloud-commitments-cli#943).
Recommending close as obsolete, not as fixed. Note frontend/src/users/userActions.ts:103 still says 000058 and is now separately stale; a fresh narrow issue for that one line would be the right follow-up.