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

docs/guides/overview.md

@@ -21,6 +21,9 @@ Direkt sichtbar: `lit-guide`, `lit-site-status`, `lit-content-types`, `lit-conte
 `lit-content-get`, `lit-content-create`, `lit-content-update`, `lit-post-publish`, `lit-media-search`,
 `lit-media-preview`, `lit-media-download`, `lit-media-upload-from-url`.
 
+Welche Tools direkt sichtbar sind, lässt sich unter Einstellungen → LIT MCP → Tools ändern (außer bei
+`lit-guide`, das immer direkt bleibt).
+
 Über `mcp-adapter-discover-abilities` / `mcp-adapter-execute-ability` (Ability-Namen `lit/…`; in Guides und
 Hinweisen immer so geschrieben):
 Status (`lit/post-unpublish`, `lit/post-schedule`, `lit/post-trash`), Kopien (`lit/post-duplicate`,