feat(accounts): add target platform usage windows

[CatStack-pixe]

Summary\n- Add dedicated 7-day token-point and 24-hour request windows to Admin Accounts.\n- Calculate the display from local usage logs because the provider account API does not expose a numeric per-key free balance.\n- Keep provider point exhaustion visible as a separate account status.\n- Treat the target platform request counter as observational: local scheduler admission and request reservation do not stop at the local 100-request counter.\n- Preserve the existing request-quota gate for other platforms.\n\n## Online findings\n- Read-only audit found 32 target-platform accounts in group 47: 11 active and schedulable, 21 in error and unschedulable.\n- The 21 upstream failures are HTTP 403 responses indicating insufficient 7-day free points.\n- Public limits shown in the supplied pricing reference are 50,000 token points per 7 days and 100 requests per 24 hours.\n\n## Verification\n- Targeted Vitest: 49 passed.\n- �ue-tsc --noEmit: passed.\n- Frontend build: passed.\n- ESLint: zero errors; two pre-existing warnings.\n- Full frontend suite: 265 passed; five unrelated test files report four existing failures.\n- Backend Go tests are pending because Go, gofmt, Docker, and WSL Go tooling are unavailable in the workspace.

[CatStack-pixe]

Audit result: no blocking defect found in the changed paths.\n\n- The target platform uses local 24-hour request and 7-day token observations for the Admin Accounts window.\n- The target platform bypasses only the local request-quota admission gate; monetary and other account quota checks remain unchanged.\n- Provider point exhaustion is surfaced separately, and no numeric upstream per-key balance is fabricated.\n- Added backend and frontend regression coverage for window calculation, values above the local request reference, provider point errors, and the dedicated account-cell render path.\n- Local validation passed for targeted Vitest (49 tests), vue-tsc, frontend build, and ESLint with zero errors.\n- Residual limitation: the workspace lacks Go tooling, while the initial CI backend tests passed; the current CI rerun is still pending.