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-Installation.md

@@ -28,7 +28,7 @@ KST4Contest automatically adapts the main window to the available area of the pr
 
 ### Java
 
-The ready-made packages from the [GitHub Releases](https://github.com/praktimarc/kst4contest/releases/latest) do not require a separate Java installation. The required runtime is distributed with KST4Contest.
+The ready-made packages from the [GitHub Releases](https://github.com/HamRadioOnline/kst4contest/releases/latest) do not require a separate Java installation. The required runtime is distributed with KST4Contest.
 
 A Java development environment is only required if you want to build KST4Contest from source. For the AUR packages `kst4contest` and `kst4contest-git`, Java 21 and Maven are handled as build dependencies by the package manager.
 
@@ -56,8 +56,8 @@ If a function in this manual is explicitly marked as **Nightly**, it is not nece
 
 The current Stable version is available here:
 
-- [Latest KST4Contest release](https://github.com/praktimarc/kst4contest/releases/latest)
-- [All published releases](https://github.com/praktimarc/kst4contest/releases)
+- [Latest KST4Contest release](https://github.com/HamRadioOnline/kst4contest/releases/latest)
+- [All published releases](https://github.com/HamRadioOnline/kst4contest/releases)
 
 The release page contains the application packages as well as the English and German PDF manuals.
 
@@ -151,7 +151,7 @@ The repository only needs to be added once:
 
 ```bash
 flatpak remote-add --if-not-exists kst4contest \
-https://praktimarc.github.io/kst4contest/kst4contest.flatpakrepo
+https://hamradioonline.github.io/kst4contest/kst4contest.flatpakrepo
 ```
 
 You can then install the Stable version:
@@ -427,14 +427,14 @@ KST4Contest is not currently signed with a commercial Windows code-signing certi
 
 Check the following first:
 
-- Did the file come from the [official KST4Contest release](https://github.com/praktimarc/kst4contest/releases/latest)?
+- Did the file come from the [official KST4Contest release](https://github.com/HamRadioOnline/kst4contest/releases/latest)?
 - Does the filename match the published release?
 - Was the file downloaded completely?
 - Does the security product report a specific detection name or only a general reputation warning?
 
 A warning alone is neither reliable proof of malware nor automatically a false positive. If the origin of the file is unclear, do not run it or restore it from quarantine.
 
-Some users have reported quarantine messages from Norton 360 in particular. If the warning can be reproduced, please create a [GitHub issue](https://github.com/praktimarc/kst4contest/issues) and include:
+Some users have reported quarantine messages from Norton 360 in particular. If the warning can be reproduced, please create a [GitHub issue](https://github.com/HamRadioOnline/kst4contest/issues) and include:
 
 - the KST4Contest version,
 - the complete filename,
@@ -460,7 +460,7 @@ On older versions the block is expected. Use the **Open** function described und
 
 ### The problem remains
 
-First check whether the problem has already been reported under [GitHub Issues](https://github.com/praktimarc/kst4contest/issues). If it has not, create a new issue containing:
+First check whether the problem has already been reported under [GitHub Issues](https://github.com/HamRadioOnline/kst4contest/issues). If it has not, create a new issue containing:
 
 - the operating system and version,
 - the KST4Contest version,