Studio: post-merge build fixes — drop dead score handling, dedupe activeThreadId, add knowledgeBases i18n key

Follow-ups after merging origin/main into feature/rag:

* chat-adapter.ts: drop `score` field from DocumentSourcePart and the
  `chunk.score` copy — the remote "hide RAG retrieval scores from chunks,
  citations, and side panel" commit removed `score` from ParsedChunk.
* chat-settings-sheet.tsx: remove the duplicate `const activeThreadId =`
  introduced by the merge (kept the HEAD-side declaration at line 497).
* chat-settings-sheet.tsx: drop the "Min relevance" Slider that referenced
  `ragMinScore` / `setRagMinScore` — same intent as the hide-scores commit
  (these are still on the runtime store but the side-panel UI is gone).
* i18n locales (en, zh-CN): add `settings.tabs.knowledgeBases` translation
  key so the new TabDef entry passes the TranslationKey union check.

Verified: `tsc --noEmit` clean, `vite build` succeeds.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

studio/frontend/src/features/chat/api/chat-adapter.ts

@@ -401,7 +401,6 @@ interface DocumentSourcePart {
   pageCharEnd?: string;
   lineStart?: string;
   lineEnd?: string;
-  score?: string;
   text: string;
 }
 
@@ -477,9 +476,6 @@ function toDocumentSourcePart(
   if (chunk.lineEnd) {
     part.lineEnd = chunk.lineEnd;
   }
-  if (chunk.score) {
-    part.score = chunk.score;
-  }
 
   return part;
 }

studio/frontend/src/features/chat/chat-settings-sheet.tsx

@@ -712,7 +712,6 @@ export function ChatSettingsPanel({
       activeExternalProvider.providerType,
       externalSelection?.modelId,
     );
-  const activeThreadId = useChatRuntimeStore((s) => s.activeThreadId);
   const openAiApiKeyForSection = activeExternalProvider
     ? getExternalProviderApiKey(activeExternalProvider.id) || null
     : null;
@@ -1658,30 +1657,6 @@ export function ChatSettingsPanel({
                     grounding, more tokens.
                   </p>
                 </div>
-                <div className="flex flex-col gap-1.5">
-                  <div className="flex items-center justify-between">
-                    <label className="text-[12px] font-medium text-muted-foreground">
-                      Min relevance
-                    </label>
-                    <span className="text-[12px] tabular-nums text-muted-foreground">
-                      {ragMinScore === 0 ? "off" : ragMinScore.toFixed(2)}
-                    </span>
-                  </div>
-                  <Slider
-                    value={[ragMinScore]}
-                    min={0}
-                    max={1}
-                    step={0.05}
-                    onValueChange={([v]) => v != null && setRagMinScore(v)}
-                    disabled={!ragEnabled}
-                  />
-                  <p className="text-[11px] text-muted-foreground">
-                    Cosine-similarity floor for retrieved chunks (0 = off). Set
-                    above 0 so unrelated docs are dropped — useful when your
-                    query is off-topic from what's indexed. Try 0.3 as a
-                    starting point.
-                  </p>
-                </div>
                 <div className="flex items-center justify-between">
                   <div className="flex flex-col">
                     <span className="text-[13px] font-medium">

studio/frontend/src/i18n/locales/en.ts

@@ -89,6 +89,7 @@ export const en = {
       profile: "Profile",
       appearance: "Appearance",
       chat: "Chat",
+      knowledgeBases: "Knowledge Bases",
       connections: "Connections",
       apiKeys: "API",
       about: "Help",

studio/frontend/src/i18n/locales/zh-CN.ts

@@ -89,6 +89,7 @@ export const zhCN = {
       profile: "个人资料",
       appearance: "外观",
       chat: "聊天",
+      knowledgeBases: "知识库",
       connections: "连接",
       apiKeys: "API",
       about: "帮助",