feat: tools and limits settings tabs

Adds Einstellungen → LIT MCP → Tools (direct/indirect/disabled per
ability, only ExposurePolicy-allowed modes offered) and → Limits
(upload size, log retention, snapshot count), wired into Plugin.php.

Ruling Q11b (carried from task 6): overview.md notes that direct
visibility is configurable; hints in src/ that name a tool which is
direct by default but can be switched to indirect (content-get,
content-query, content-types, post-publish, media-search) now use the
neutral "lit/<name> (direkt: lit-<name>)" form so they stay correct
after an admin override. lit/guide (always direct) and the
media-preview/-download DIRECT_ONLY tools are unaffected.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

src/Guides/InstructionsBuilder.php

@@ -49,7 +49,7 @@ final class InstructionsBuilder
 
         if ($this->postTypeNames !== null) {
             $lines[] = 'Inhaltstypen: ' . implode(', ', ($this->postTypeNames)())
-                . ' (Felder und Taxonomien: lit-content-types).';
+                . ' (Felder und Taxonomien: lit/content-types, direkt: lit-content-types).';
         }
 
         return implode("\n", array_merge($lines, [