List routers

Lists Router records in the active tenant/subscription/project scope, powering the Routers page table. This single endpoint serves both the plain route-load listing and the search/filter/sort/pagination controls: q performs a case-insensitive substring match on the router name, status narrows by lifecycle state (the "Active" counter chip), ha narrows to high-availability routers (the "HA" counter chip), and sort/order support the sortable columns (name, createdAt). Each row carries the external gateway (with SNAT flag and external IP), interface count, static-route count, HA/DVR markers, and creation time. Validation: scopeId must resolve to a scope the caller can read, else 403/404 semantics apply; malformed query parameters (unknown status value, non-boolean ha, page/pageSize out of range) → 422 VALIDATION_FAILED. Async & state: Synchronous read; no state change. Results reflect the latest read model including routers still in transitional BUILD state and routers undergoing async deletion. Errors: 401 when unauthenticated; 403 when the caller lacks reader access to the scope; 422 on malformed query parameters; 500 on backend read-model failure. Idempotency/Concurrency: Safe, cacheable; no idempotency key required. Pagination cursors remain stable across repeated calls with identical parameters.