feat(ui): replace unicode icons with solid-icons

Swap emoji and unicode glyphs for Tabler components so icons inherit
currentColor and font-size and render consistently across platforms.

- add src/components/doc-icons.ts to resolve doc-entry frontmatter icon
  keys to components; frontmatter now stores semantic keys
- replace the align-*.png assets with TbOutlineAlign* icons
- render RevealManager action SVGs as components instead of injected
  innerHTML strings
- carry completion icons via an optional CompletionItem.icon field

src/components/journal/ConnectDialog.tsx

@@ -6,6 +6,7 @@
  * or creating a session is a separate step that reuses that connection.
  */
 import { Component, createSignal, For, onMount, Show } from "solid-js";
+import { TbOutlineTrash } from "solid-icons/tb";
 import {
   connectBroker,
   createSession,
@@ -167,7 +168,7 @@ export const ConnectDialog: Component = () => {
                       class="shrink-0 px-2 py-1.5 text-[10px] text-gray-300 hover:text-red-500 disabled:opacity-50"
                       title="删除会话"
                     >
-                      🗑
+                      <TbOutlineTrash />
                     </button>
                   </Show>
                 </div>