feat: switch to PaperMod theme, add Rybbit analytics, CI/CD deploy

- Replace ananke with PaperMod theme (git submodule)
- Configure PaperMod: reading time, breadcrumbs, search, dark mode
- Localize menus for EN/DE
- Register internetforkids.ong in Rybbit (site ID: a0ab05916d6c)
- Migrate partials from ananke _partials/ to PaperMod extend_head/footer
- Set up webhook-based auto-deploy on push to main

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

layouts/partials/extend_head.html

@@ -13,13 +13,9 @@
 <link rel="canonical" href="{{ .Permalink }}" />
 
 {{/* AI Search Engine Optimization */}}
-{{/* Allow all AI crawlers — maximize discoverability */}}
 <meta name="robots" content="index, follow, max-snippet:-1, max-image-preview:large" />
-
-{{/* Explicit AI crawler permissions */}}
 <meta name="googlebot" content="index, follow" />
 
-{{/* Clear, machine-parseable description for AI summarization */}}
 {{ if .IsPage }}
 <meta name="topic" content="{{ .Title }}" />
 <meta name="subject" content="{{ .Description | default .Summary | plainify | truncate 160 }}" />