docs: restructure README to English-first, fix CHANGELOG date, update llms.txt

- README restructured: English is now the primary language with full
  feature docs, keyboard shortcuts, installation, and roadmap sections;
  German content moved to a secondary "Deutsch / German" section
- CHANGELOG: replaced placeholder YYYY-MM-DD with actual 2026-02-24
  initial release date
- llms.txt: added web_companion entry, three new search phrases, and
  last-checked marker

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Lukas Geiger

CHANGELOG.md

@@ -34,7 +34,7 @@ Format basiert auf [Keep a Changelog](https://keepachangelog.com/de/1.1.0/).
 - `WinStorePackager`: subprocess-Deadlock behoben — `check_call` mit PIPE durch `subprocess.run(..., capture_output=True)` ersetzt; Exception-Handler liest jetzt immer `stderr or stdout`.
 - `ProfilerBridge`: SQLite-Connection-Leak auf Windows geschlossen — alle 6 `conn.close()`-Stellen in `search()`, `find_duplicates()` und `get_statistics()` verwenden jetzt `try/finally`.
 
-## [1.0.0] - YYYY-MM-DD
+## [1.0.0] - 2026-02-24
 
 ### Hinzugefügt / Added
 - Erstveröffentlichung / Initial release