fix: persist draft text per conversation tab

Draft text typed in the input bar is now stored per-tab so switching
conversations no longer clears an in-progress prompt.

src/lib/components/InputBar.svelte

@@ -164,6 +164,17 @@
     attachments = storedAttachments;
   });
 
+  // Per-tab draft persistence — restore the draft text whenever the active
+  // conversation changes, and save it back on every keystroke.
+  claudeStore.activeConversationId.subscribe((conversationId) => {
+    if (conversationId) {
+      const conv = get(claudeStore.conversations).get(conversationId);
+      inputValue = conv?.draftText ?? "";
+    } else {
+      inputValue = "";
+    }
+  });
+
   function handleInputChange() {
     // If input is empty, allow history navigation again
     // Otherwise, mark that user has manually typed
@@ -176,6 +187,12 @@
     historyIndex = -1;
     tempInput = "";
 
+    // Save the current draft so it persists if the user switches tabs.
+    const activeId = get(claudeStore.activeConversationId);
+    if (activeId) {
+      claudeStore.setDraftText(activeId, inputValue);
+    }
+
     if (isSlashCommand(inputValue)) {
       matchingCommands = getMatchingCommands(inputValue);
       showCommandMenu = matchingCommands.length > 0;