fix(api-manager): preserve allowedCombos entries the Combo picker cannot render (#12397)

The API key permissions modal silently dropped allowedCombos entries its Combo picker cannot render — routing-rule names such as rt-*, which matchesComboAccessRule() already honours. Stored entries rendered as zero selected, and clicking All then Restrict then Save persisted allowedCombos: [], which is deny-all for combo requests.

Those entries now survive the All toggle, are listed read-only under the combo list so the header count and the list agree, and are saved back verbatim. The UI does not learn routing-rule semantics (option 1 from the issue). The Allowed Combos section moves out of the frozen ApiManagerPageClient.tsx into its own component following the UsageLimitSettings pattern.

Validated in a combined worktree with all 25 PRs of this batch boarded together: typecheck:core clean, 443/443 node-runner tests plus 14/14 vitest across every test file the batch touches, and check-changelog-integrity, check:cycles (418 files), check:provider-consistency (272 REGISTRY entries, 355 canonical providers), check:docs-counts, check:docs-sync (42 locales) and check-file-size all green.

Thanks @pacocartones.