feat(portal-shell): clean widget design tokens and fix lint:tokens (P1-6)

516 mechanical replacements across 25 widget files:
- spacing xs/sm/md/lg/xl to numeric 1/2/3/4/6
- text-heading-3 to text-lg font-semibold
- bg-danger to bg-destructive
- border border dedup

Fix .eslintrc.tokens.js to use typescript-eslint parser (was importing
uninstalled @typescript-eslint/parser). lint:tokens now passes.

apps/portal-shell/src/widgets/sidebar/term-switcher/index.tsx

@@ -1,4 +1,4 @@
-"use client";
+"use client";
 
 /**
  * term-switcher（sidebar / side）
@@ -42,7 +42,7 @@ export default function TermSwitcher(_props: PluginProps): React.ReactElement {
       <select
         value={selectedTermId}
         onChange={(e) => handleSelect(e.target.value)}
-        className="mt-xs w-full rounded-md border border bg-card px-sm py-xs text-sm text-foreground"
+        className="mt-1 w-full rounded-md border bg-card px-2 py-1 text-sm text-foreground"
         aria-label="选择学期"
       >
         <option value="">请选择学期</option>