fix(api): mark schema-validation errors as non-retryable

The proxy returned `{fonts: null, total: 0}` for empty results, which
fetchProxyFonts surfaced as a generic Error. fontCatalogStore wrapped it
as FontNetworkError, and TanStack retried 3× with exponential backoff —
pinning the loading skeleton for ~7s before settling on an empty list.

Schema mismatches are deterministic; retrying only delays surfacing the
contract violation.

- shared/api/queryClient: introduce NonRetryableError marker class.
  The default retry handler short-circuits when it sees this so any
  store using the shared client gets fail-fast behavior for free.
- entities/Font/lib/errors: FontResponseError extends NonRetryableError.
- entities/Font/api/proxy/proxyFonts: throw FontResponseError (was a
  bare Error). Document that ProxyFontsResponse.fonts is always an array.
- entities/Font/.../fontCatalogStore.fetchPage: preserve a
  FontResponseError raised lower in the stack instead of re-wrapping
  it as FontNetworkError.
- features/FilterAndSortFonts/api/filters: throw NonRetryableError on
  invalid filters payloads and document the array-never-null contract.

src/entities/Font/lib/errors/errors.ts

@@ -1,3 +1,5 @@
+import { NonRetryableError } from '$shared/api/queryClient';
+
 /**
  * Thrown when the network request to the proxy API fails.
  * Wraps the underlying fetch error (timeout, DNS failure, connection refused, etc.).
@@ -12,11 +14,13 @@ export class FontNetworkError extends Error {
 
 /**
  * Thrown when the proxy API returns a response with an unexpected shape.
+ * Extends NonRetryableError because schema mismatches are not transient —
+ * retrying will produce the same failure and only delay surfacing the bug.
  *
  * @property field - The name of the field that failed validation (e.g. `'response'`, `'response.fonts'`).
  * @property received - The actual value received at that field, for debugging.
  */
-export class FontResponseError extends Error {
+export class FontResponseError extends NonRetryableError {
     readonly name = 'FontResponseError';
 
     constructor(