feat(providers): add OpenAI/Claude connectivity test in edit sheet

- Introduce useConnectivityTest hook that drives per-key and bulk tests
  via apiCallApi against the chat-completions / messages endpoints, with
  signature-based status reset
- OpenAI form: each API key entry header now shows a status icon plus a
  per-key Test button, and the entries section gains a Test all button
- Claude form: enable the Test model field and add a Test button with
  inline status; falls back to the persisted apiKey when the edit form
  field is left blank
- Add ConnectivityStatusIcon, related styles (spin keyframes, buttons,
  error banner), and i18n keys (en/zh-CN/zh-TW/ru) for the test labels
  and validation messages

src/features/providers/sheets/forms/sharedForm.module.scss

@@ -207,6 +207,125 @@
   color: var(--muted-foreground);
 }
 
+.entryCardHeaderRight {
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.entriesToolbar {
+  display: flex;
+  align-items: center;
+  justify-content: flex-end;
+  gap: 8px;
+  margin-bottom: 2px;
+}
+
+.connectivityRow {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-top: 4px;
+}
+
+.connectivityBtn {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  height: 28px;
+  padding: 0 12px;
+  border-radius: var(--radius-md);
+  border: 1px solid var(--border-color);
+  background: var(--bg-primary);
+  color: var(--text-primary);
+  font-size: 12px;
+  font-weight: 500;
+  cursor: pointer;
+  transition: background-color $transition-fast, border-color $transition-fast;
+
+  &:hover:not(:disabled) {
+    border-color: var(--primary-color);
+    color: var(--primary-color);
+  }
+
+  &:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+  }
+}
+
+.connectivityBtnGhost {
+  display: inline-flex;
+  align-items: center;
+  gap: 6px;
+  height: 24px;
+  padding: 0 8px;
+  border-radius: var(--radius-md);
+  border: 1px solid transparent;
+  background: transparent;
+  color: var(--text-secondary);
+  font-size: 11px;
+  font-weight: 500;
+  cursor: pointer;
+  transition: background-color $transition-fast, color $transition-fast;
+
+  &:hover:not(:disabled) {
+    background: var(--bg-tertiary);
+    color: var(--text-primary);
+  }
+
+  &:disabled {
+    opacity: 0.6;
+    cursor: not-allowed;
+  }
+}
+
+.connectivityError {
+  border: 1px solid var(--destructive-30);
+  background: var(--destructive-10);
+  color: var(--destructive-color);
+  padding: 8px 10px;
+  border-radius: var(--radius-md);
+  font-size: 11px;
+  line-height: 1.4;
+  word-break: break-word;
+}
+
+.connectivityHintSuccess {
+  font-size: 11px;
+  color: var(--primary-color);
+}
+
+.statusIcon {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 14px;
+  height: 14px;
+}
+
+.statusIconLoading {
+  color: var(--text-secondary);
+  animation: spin 0.8s linear infinite;
+}
+
+.statusIconSuccess {
+  color: var(--primary-color);
+}
+
+.statusIconError {
+  color: var(--destructive-color);
+}
+
+@keyframes spin {
+  from {
+    transform: rotate(0deg);
+  }
+  to {
+    transform: rotate(360deg);
+  }
+}
+
 .entriesList {
   display: flex;
   flex-direction: column;