feat: add create and delete file/folder functionality to editor

- Add Tauri backend commands: create_file, create_directory, delete_file, delete_directory
- Add editor store functions for create/delete with auto-refresh
- Add FileContextMenu component with right-click support
- Add InputDialog component for file/folder name input
- Add ConfirmDialog component for delete confirmation
- Add Ctrl+N keyboard shortcut for new file
- Update keyboard shortcuts modal with new shortcuts
- Auto-close tabs when their files are deleted
- Auto-refresh file tree after create/delete operations

src/lib/components/editor/InputDialog.svelte

@@ -0,0 +1,80 @@
+<script lang="ts">
+  interface Props {
+    title: string;
+    placeholder?: string;
+    confirmText?: string;
+    cancelText?: string;
+    onConfirm: (value: string) => void;
+    onCancel: () => void;
+  }
+
+  let {
+    title,
+    placeholder = "",
+    confirmText = "Create",
+    cancelText = "Cancel",
+    onConfirm,
+    onCancel,
+  }: Props = $props();
+
+  let inputValue = $state("");
+  let inputElement: HTMLInputElement | undefined = $state();
+
+  $effect(() => {
+    if (inputElement) {
+      inputElement.focus();
+    }
+  });
+
+  function handleSubmit() {
+    const trimmed = inputValue.trim();
+    if (trimmed) {
+      onConfirm(trimmed);
+    }
+  }
+
+  function handleKeydown(event: KeyboardEvent) {
+    if (event.key === "Escape") {
+      onCancel();
+    } else if (event.key === "Enter") {
+      handleSubmit();
+    }
+  }
+</script>
+
+<svelte:window onkeydown={handleKeydown} />
+
+<!-- svelte-ignore a11y_no_static_element_interactions -->
+<div class="fixed inset-0 z-50 flex items-center justify-center bg-black/50" onclick={onCancel}>
+  <!-- svelte-ignore a11y_no_static_element_interactions -->
+  <div
+    class="mx-4 w-full max-w-md rounded-lg border border-gray-700 bg-gray-800 p-6 shadow-xl"
+    onclick={(e) => e.stopPropagation()}
+  >
+    <h2 class="mb-4 text-lg font-semibold text-gray-100">{title}</h2>
+
+    <input
+      bind:this={inputElement}
+      bind:value={inputValue}
+      type="text"
+      {placeholder}
+      class="mb-6 w-full rounded-md border border-gray-600 bg-gray-700 px-3 py-2 text-sm text-gray-100 placeholder-gray-400 focus:border-pink-500 focus:outline-none focus:ring-1 focus:ring-pink-500"
+    />
+
+    <div class="flex justify-end gap-3">
+      <button
+        class="rounded-md border border-gray-600 bg-gray-700 px-4 py-2 text-sm text-gray-200 hover:bg-gray-600"
+        onclick={onCancel}
+      >
+        {cancelText}
+      </button>
+      <button
+        class="rounded-md bg-pink-600 px-4 py-2 text-sm text-white hover:bg-pink-700 disabled:cursor-not-allowed disabled:opacity-50"
+        onclick={handleSubmit}
+        disabled={!inputValue.trim()}
+      >
+        {confirmText}
+      </button>
+    </div>
+  </div>
+</div>