fix: arrow keys navigate cursor when user has typed input

- Added userHasTyped flag to track manual input vs history navigation
- Arrow keys only navigate history when input is empty or from history
- Clearing input re-enables history navigation

Closes #58

src/lib/components/InputBar.svelte

@@ -38,6 +38,7 @@
   let inputHistory = $state<string[]>([]);
   let historyIndex = $state(-1);
   let tempInput = $state("");
+  let userHasTyped = $state(false); // Track if user manually typed (vs history navigation)
 
   // Textarea resize state
   let textareaHeight = $state(48);
@@ -112,6 +113,13 @@
   });
 
   function handleInputChange() {
+    // If input is empty, allow history navigation again
+    // Otherwise, mark that user has manually typed
+    if (inputValue === "") {
+      userHasTyped = false;
+    } else {
+      userHasTyped = true;
+    }
     // Reset history navigation when user types
     historyIndex = -1;
     tempInput = "";
@@ -156,6 +164,7 @@
       addToHistory(message);
       historyIndex = -1;
       tempInput = "";
+      userHasTyped = false;
 
       const wasCommand = await executeSlashCommand();
       if (wasCommand) return;
@@ -175,6 +184,7 @@
     addToHistory(message);
     historyIndex = -1;
     tempInput = "";
+    userHasTyped = false;
 
     isSubmitting = true;
     inputValue = "";
@@ -308,8 +318,9 @@ User: ${formattedMessage}`;
       }
     }
 
-    // Handle input history navigation (when command menu is closed)
-    if (event.key === "ArrowUp" && inputHistory.length > 0) {
+    // Handle input history navigation (when command menu is closed AND user hasn't typed)
+    // If user has typed something, let arrow keys navigate the cursor instead
+    if (event.key === "ArrowUp" && inputHistory.length > 0 && !userHasTyped) {
       event.preventDefault();
       if (historyIndex === -1) {
         // Save current input before navigating history
@@ -322,12 +333,13 @@ User: ${formattedMessage}`;
       return;
     }
 
-    if (event.key === "ArrowDown" && historyIndex >= 0) {
+    if (event.key === "ArrowDown" && historyIndex >= 0 && !userHasTyped) {
       event.preventDefault();
       historyIndex--;
       if (historyIndex === -1) {
         // Restore the temp input when going back to current
         inputValue = tempInput;
+        userHasTyped = false; // Reset since we're back to empty/temp state
       } else {
         inputValue = inputHistory[historyIndex];
       }