Update repository URLs to HamRadioOnline organisation (#142)

* Move remaining references to the HamRadioOnline organisation

The repository moved from praktimarc/kst4contest to
HamRadioOnline/kst4contest. Document the move in the German and English
changelog, point manuals, README, website, AUR packaging and the
version-feed tooling at the new address, and keep accepting pre-move
release URLs in the update-feed validator because published feeds still
carry the old owner. Personal identities (Ko-Fi account, contact
e-mail) stay unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WFGQ7wkSPo21itLMHPi8Yw

* Lowercase the owner in the generated Flatpak Pages URL

GITHUB_REPOSITORY_OWNER is now the mixed-case HamRadioOnline, and the
next build would write that spelling into the published flatpakrepo and
flatpakref files. Hostnames are case-insensitive, but the published
metadata should match the documented lowercase address.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WFGQ7wkSPo21itLMHPi8Yw

* Build the Flatpak against org.freedesktop.Platform 25.08

Runtime branch 24.08 is end-of-life and no longer receives security
updates, so every flatpak update now prints an EOL warning. 25.08 is
the current supported branch on Flathub. The app bundles its own Java
runtime, so the platform bump only changes the base libraries.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WFGQ7wkSPo21itLMHPi8Yw

---------

Co-authored-by: Claude <noreply@anthropic.com>

github_docs/en-Home.md

@@ -4,7 +4,7 @@
 
 KST4Contest is a desktop client for the [ON4KST Chat](https://www.on4kst.org/chat/login.php), developed for VHF, UHF and SHF contest operation. It brings chat, candidate selection, sked planning, aircraft scatter data and external station software together in a single operating interface.
 
-KST4Contest is developed by **DO5AMF (Marc Fröhlich)**, operator at DM5M and (since May 2025) **DN9APW (Philipp Wagner)**. The source code is publicly available on [GitHub](https://github.com/praktimarc/kst4contest).
+KST4Contest is developed by **DO5AMF (Marc Fröhlich)**, operator at DM5M and (since May 2025) **DN9APW (Philipp Wagner)**. The source code is publicly available on [GitHub](https://github.com/HamRadioOnline/kst4contest).
 
 ---
 
@@ -57,7 +57,7 @@ The currently published Stable version is **v1.42.0**.
 Functions that are only available in a Beta or Nightly build are marked accordingly. If no such note is present, the description applies to the stable release.
 
 - [Download Stable, Beta and Nightly builds](https://kst4contest.hamradioonline.de/download/)
-- [GitHub releases](https://github.com/praktimarc/kst4contest/releases)
+- [GitHub releases](https://github.com/HamRadioOnline/kst4contest/releases)
 - [Version history](en-Changelog)
 
 The stable release is normally the appropriate choice for contest operation. Beta and Nightly builds contain newer fixes and functions, but may still change between builds. They are intended for testing specific changes. Ten minutes before a contest is usually not the ideal time for a first test.
@@ -84,8 +84,8 @@ The stable release is normally the appropriate choice for contest operation. Bet
 ## Contact and support
 
 - **Download:** [Stable, Beta and Nightly builds](https://kst4contest.hamradioonline.de/download/)
-- **Source code:** [praktimarc/kst4contest](https://github.com/praktimarc/kst4contest)
-- **Bug reports and feature requests:** [GitHub Issues](https://github.com/praktimarc/kst4contest/issues)
+- **Source code:** [HamRadioOnline/kst4contest](https://github.com/HamRadioOnline/kst4contest)
+- **Bug reports and feature requests:** [GitHub Issues](https://github.com/HamRadioOnline/kst4contest/issues)
 - **Email:** praktimarc+kst4contest@gmail.com  
   Please use this address only for KST4Contest-related topics.