Refactor VPN proxy client implementation

docs/product/error-contract.md

@@ -15,7 +15,7 @@ Public API failures use one envelope:
 }
 ```
 
-`code`, Russian user copy, HTTP status and retry policy come from `src/shared/errors.js`. The browser maps copy and retry behavior by `code`; it does not display server-provided `details`. Unknown failures use `UNKNOWN`, never expose the raw exception, and always receive a correlation reference. Server logs use the same reference and redact complete HTTP(S) URLs.
+`code`, Russian user copy, HTTP status and retry policy come from `src/shared/errors.ts`. The browser maps copy and retry behavior by `code`; it does not display server-provided `details`. Unknown failures use `UNKNOWN`, never expose the raw exception, and always receive a correlation reference. Server logs use the same reference and redact complete HTTP(S) URLs.
 
 Errors are local operation results, not canonical state replacements. A failed apply keeps the previous snapshot; in particular, server existence is validated before `desiredServerId` is persisted. Frontend errors are shown beside subscription or connection controls. Only retryable codes expose `Повторить`.
 

docs/product/frontend-operations.md

@@ -7,7 +7,7 @@ Harbor tracks active browser mutations by operation key instead of one global `b
 - `subscriptionImport`, `subscriptionRefresh`, `subscriptionDelete`;
 - `gatewayAuto`: change the active route preference.
 
-Each entry is `{ status: "running", startedAt }`. A repeated operation key receives the same in-flight Promise, so a double click sends one request. A conflicting key resolves to `false` without starting its action. The symmetric conflict matrix lives in `src/web/state/operations.js`.
+Each entry is `{ status: "running", startedAt }`. A repeated operation key receives the same in-flight Promise, so a double click sends one request. A conflicting key resolves to `false` without starting its action. The symmetric conflict matrix lives in `src/web/state/operations.ts`.
 
 The registry only disables controls that can mutate the same domain state. Copy actions, instruction navigation and local tabs remain available during subscription refresh. Progress is announced with `role="status"`; the structured error from TASK-004 remains `role="alert"` after failure.