refactor(frontend): unify Tailwind classes — replace hardcoded colors with semantic design tokens

- Replace all bg-blue-600/hover:bg-blue-700 → bg-primary/hover:bg-primary-hover
- Replace all bg-red-600/hover:bg-red-700 → bg-destructive/hover:bg-destructive-hover
- Replace all focus:ring-blue-500 → focus-visible:ring-primary-ring
- Replace all text-blue-600 → text-primary on interactive elements
- Replace all bg-blue-50 → bg-primary-light on UI surfaces
- Replace all bg-red-50 → bg-destructive-light on error surfaces
- Replace all border-blue-200/300 → border-primary-ring
- Replace all border-red-200 → border-destructive-light
- Replace peer-checked:bg-blue-600 → peer-checked:bg-primary (toggles)
- Replace focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-blue-500 patterns
- Keep status badge patterns (bg-*-100 text-*-700) and hover:bg-blue-50 intact

82 files changed, ~400 changes. Build passes.

frontend/src/components/git/GitWorkspacePanel.svelte

@@ -42,7 +42,7 @@
       <div class="mb-2 flex items-center justify-between">
         <h3 class="text-sm font-semibold text-slate-700">Сообщение коммита</h3>
         <button
-          class="inline-flex items-center text-xs text-blue-600 hover:text-blue-800 disabled:opacity-50"
+          class="inline-flex items-center text-xs text-primary hover:text-blue-800 disabled:opacity-50"
           onclick={onGenerateMessage}
           disabled={generatingMessage || workspaceLoading}
         >
@@ -51,7 +51,7 @@
       </div>
       <textarea
         bind:value={commitMessage}
-        class={`h-36 w-full resize-none rounded border p-2 outline-none focus:ring-2 focus:ring-blue-500 ${generatingMessage ? 'animate-pulse bg-slate-100' : ''}`}
+        class={`h-36 w-full resize-none rounded border p-2 outline-none focus-visible:ring-2 focus-visible:ring-primary-ring ${generatingMessage ? 'animate-pulse bg-slate-100' : ''}`}
         placeholder="Опишите изменения..."
       ></textarea>
     </div>