feat(citations): inline citation links with [citation:Title](URL)

- Backend: add citation format to lead_agent and general_purpose prompts
- Add CitationLink component (Badge + HoverCard) for citation cards
- MarkdownContent: detect citation: prefix in link text, render CitationLink
- Message/artifact/subtask: use MarkdownContent or Streamdown with CitationLink
- message-list-item: pass img via components prop (remove isHuman/img)
- message-group, subtask-card: drop unused imports; fix import order (lint)

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/workspace/messages/subtask-card.tsx

@@ -19,14 +19,12 @@ import { ShineBorder } from "@/components/ui/shine-border";
 import { useI18n } from "@/core/i18n/hooks";
 import { hasToolCalls } from "@/core/messages/utils";
 import { useRehypeSplitWordsIntoSpans } from "@/core/rehype";
-import {
-  streamdownPlugins,
-  streamdownPluginsWithWordAnimation,
-} from "@/core/streamdown";
+import { streamdownPluginsWithWordAnimation } from "@/core/streamdown";
 import { useSubtask } from "@/core/tasks/context";
 import { explainLastToolCall } from "@/core/tools/utils";
 import { cn } from "@/lib/utils";
 
+import { CitationLink } from "../citations/citation-link";
 import { FlipDisplay } from "../flip-display";
 
 import { MarkdownContent } from "./markdown-content";
@@ -128,7 +126,10 @@ export function SubtaskCard({
           {task.prompt && (
             <ChainOfThoughtStep
               label={
-                <Streamdown {...streamdownPluginsWithWordAnimation}>
+                <Streamdown 
+                  {...streamdownPluginsWithWordAnimation}
+                  components={{ a: CitationLink }}
+                >
                   {task.prompt}
                 </Streamdown>
               }