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/md-pins.tsx

@@ -1,5 +1,6 @@
 import { customElement, noShadowDOM } from "solid-element";
 import {Show, For, createResource, createMemo, createSignal} from "solid-js";
+import { TbOutlineCopy } from "solid-icons/tb";
 import { resolvePath } from "./utils/path";
 import { createPinsStore } from "./stores/pinsStore";
 
@@ -108,7 +109,7 @@ customElement("md-pins", { pins: "", fixed: false, labelStart: "A" }, (props, {
                 class="bg-gray-800 hover:bg-gray-700 text-white px-3 py-1.5 rounded shadow-lg text-sm flex items-center gap-1 transition-colors"
                 title="复制所有 pin 坐标"
               >
-                📋 复制
+                <TbOutlineCopy /> 复制
               </button>
             </div>
           </Show>