Publish the wiki through a reusable workflow; this wiki moves to docs/wiki

- publish-wiki-pages.yml: reusable workflow with wiki_dir, prune and
  tools-ref inputs and the declared secret TOKEN_FOR_GITEA_WIKI
- tools/publish_wiki.py: WIKI_PRUNE selects explicit mode without the marker;
  a missing folder is a configuration error
- publish-own-wiki.yml: this repository calls the reusable workflow
- wiki/ moves to docs/wiki/; build_wiki.py and its tests follow
- the scoped publish-wiki.yml is marked deprecated, not removed
- guides, README and the Danish and Bahasa Malaysia wiki pages describe the
  caller, docs/wiki/ and the new error messages

Task: MIL-008#2
Task: MIL-008#4
Task: MIL-008#5
Task: MIL-008#6

docs/wiki/_Sidebar.md

@@ -0,0 +1,39 @@
+<!-- Generated by tools/build_wiki.py. Edit the generator, not this page. -->
+
+**TirSystem GitHub Actions**
+
+**English**
+
+- [Home](Home)
+- [Onboarding](Onboarding)
+- [Credentials](Credentials)
+- [Troubleshooting](Troubleshooting)
+- [Quality checks (Python, shell)](QualityChecksPythonShell)
+- [Quality checks (C and C++)](QualityChecksCpp)
+- [Quality checks (C#)](QualityChecksCSharp)
+- [Upgrading](Upgrading)
+- [Capabilities](Capabilities)
+
+**Dansk**
+
+- [Hjem](Home.da)
+- [Tilslutning](Onboarding.da)
+- [Credentials](Credentials.da)
+- [Fejlfinding](Troubleshooting.da)
+- [Kvalitetskontrol (Python, shell)](QualityChecksPythonShell.da)
+- [Kvalitetskontrol (C og C++)](QualityChecksCpp.da)
+- [Kvalitetskontrol (C#)](QualityChecksCSharp.da)
+- [Opgradering](Upgrading.da)
+- [Kapabiliteter](Capabilities.da)
+
+**Bahasa Melayu**
+
+- [Utama](Home.ms)
+- [Menyertakan](Onboarding.ms)
+- [Kelayakan](Credentials.ms)
+- [Diagnosis](Troubleshooting.ms)
+- [Semakan kualiti (Python, shell)](QualityChecksPythonShell.ms)
+- [Semakan kualiti (C dan C++)](QualityChecksCpp.ms)
+- [Semakan kualiti (C#)](QualityChecksCSharp.ms)
+- [Menaik taraf](Upgrading.ms)
+- [Keupayaan](Capabilities.ms)