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-table.tsx

@@ -7,6 +7,7 @@ import {
   createMemo,
   createResource,
 } from "solid-js";
+import { TbOutlineDice5 } from "solid-icons/tb";
 import { parseMarkdown } from "../markdown";
 import { parseCSVString, CSV, processVariables } from "./utils/csv-loader";
 import { resolveContentRef } from "./utils/resolve-content";
@@ -210,7 +211,7 @@ customElement(
                   class="text-gray-500 hover:text-gray-700 shrink-0 cursor-pointer"
                   title="随机切换"
                 >
-                  🎲
+                  <TbOutlineDice5 class="inline-block align-[-0.125em]" />
                 </button>
               </Show>
               <div