fix(web): error text uses error-fg on every surface, not only on tints (#3150)

Raw error red fails AA as text even with no tint behind it: in dark mode
it measures 3.63:1 on obsidian, 3.23 on iron and 2.64 on slate, against
4.5. error-fg (the house formula, 50% toward parchment) measures 5.30 at
worst across both modes.

- All 19 text-error uses become text-error-fg: the "Couldn't load"
  messages on the admin pages, the integrations form errors, the flag
  popover, and the error toast's text. The toast keeps its error border,
  since a border is a graphic with a 3:1 floor.
- check-tint-contrast flags raw error text anywhere (text-error,
  class:text-error, color: var(--fs-error)) and leaves borders and
  outlines alone. Run against the files before the swap, it finds all 19.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/routes/admin/integrations/+page.svelte

@@ -463,7 +463,7 @@
         {/each}
       </select>
       {#if testListErrors.quality_profiles}
-        <p class="mt-1 text-xs text-error">
+        <p class="mt-1 text-xs text-error-fg">
           Couldn't fetch quality profiles — {testListErrors.quality_profiles}
         </p>
       {/if}
@@ -481,7 +481,7 @@
         {/each}
       </select>
       {#if testListErrors.metadata_profiles}
-        <p class="mt-1 text-xs text-error">
+        <p class="mt-1 text-xs text-error-fg">
           Couldn't fetch metadata profiles — {testListErrors.metadata_profiles}
         </p>
       {/if}
@@ -501,7 +501,7 @@
         {/each}
       </select>
       {#if testListErrors.root_folders}
-        <p class="mt-1 text-xs text-error">
+        <p class="mt-1 text-xs text-error-fg">
           Couldn't fetch root folders — {testListErrors.root_folders}
         </p>
       {/if}
@@ -513,11 +513,11 @@
           Connected — Lidarr {testResult.version}
         </p>
       {:else}
-        <p class="text-sm text-error">Connection failed — {testResult.error}</p>
+        <p class="text-sm text-error-fg">Connection failed — {testResult.error}</p>
       {/if}
     {/if}
     {#if saveError}
-      <p class="text-sm text-error">Save failed — {saveError}</p>
+      <p class="text-sm text-error-fg">Save failed — {saveError}</p>
     {/if}
 
     <div class="flex items-center gap-2 pt-2">
@@ -625,7 +625,7 @@
                     OK{coverTestResults[provider.id].duration_ms ? ` (${coverTestResults[provider.id].duration_ms}ms)` : ''}
                   </p>
                 {:else}
-                  <p class="text-sm text-error">
+                  <p class="text-sm text-error-fg">
                     Failed — {coverTestResults[provider.id].error}
                   </p>
                 {/if}
@@ -722,7 +722,7 @@
                     OK{tagTestResults[provider.id].duration_ms ? ` (${tagTestResults[provider.id].duration_ms}ms)` : ''}
                   </p>
                 {:else}
-                  <p class="text-sm text-error">
+                  <p class="text-sm text-error-fg">
                     Failed — {tagTestResults[provider.id].error}
                   </p>
                 {/if}
@@ -837,7 +837,7 @@
     class="mt-3 w-full rounded-md border border-border bg-background px-3 py-2 font-mono text-sm text-text-primary placeholder:text-text-muted focus:outline-none focus:ring-2 focus:ring-accent"
   />
   {#if disconnectError}
-    <p class="mt-2 text-sm text-error">Disconnect failed — {disconnectError}</p>
+    <p class="mt-2 text-sm text-error-fg">Disconnect failed — {disconnectError}</p>
   {/if}
   <div class="mt-5 flex justify-end gap-2">
     <button