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

.gitea/scoped_workflows/publish-wiki.yml

@@ -1,5 +1,10 @@
 name: Publish wiki
 
+# DEPRECATED (ADR-0009, MIL-008): repositories publish their wiki by calling
+# the reusable workflow publish-wiki-pages.yml. This scoped workflow stays
+# until every repository that has wiki/.publish has migrated; it is then
+# removed in a later major release.
+
 # Shared through scoped delivery: it runs in every repository of an
 # organization, but writes only where the repository has opted in with
 # wiki/.publish (ADR-0004). TOKEN_FOR_GITEA_WIKI is read from the organization

.gitea/workflows/publish-own-wiki.yml

@@ -0,0 +1,25 @@
+name: Publish own wiki
+
+# Publishes the wiki of this repository from docs/wiki/ by calling the
+# reusable workflow of this repository (ADR-0009, MIL-008 task 4). It is the
+# caller a project copies from framework/templates/ci/publish-wiki.yml, with
+# two differences: the reusable workflow is called by its local path, and
+# tools-ref is main so that the script that is run is the one of this commit.
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - "docs/wiki/**"
+  workflow_dispatch:
+
+jobs:
+  wiki:
+    permissions:
+      contents: read
+    uses: ./.gitea/workflows/publish-wiki-pages.yml
+    with:
+      wiki_dir: docs/wiki
+      prune: "true"
+      tools-ref: main
+    secrets:
+      TOKEN_FOR_GITEA_WIKI: ${{ secrets.TOKEN_FOR_GITEA_WIKI }}

.gitea/workflows/publish-wiki-pages.yml

@@ -0,0 +1,64 @@
+name: Publish wiki
+
+# Reusable workflow (ADR-0009, MIL-008). A repository calls it with
+#
+#   on:
+#     push:
+#       branches: [ main ]
+#       paths: [ "docs/wiki/**" ]
+#   jobs:
+#     wiki:
+#       uses: TirSystem/github-action/.gitea/workflows/publish-wiki-pages.yml@v1
+#       secrets:
+#         TOKEN_FOR_GITEA_WIKI: ${{ secrets.TOKEN_FOR_GITEA_WIKI }}
+#
+# The caller file is the opt-in; there is no marker file. It publishes the
+# Markdown pages of wiki_dir to the wiki of the calling repository, creating
+# and updating pages, and deleting pages that are not in the folder only when
+# prune is true. The script is a file of this repository
+# (tools/publish_wiki.py), fetched at tools-ref.
+on:
+  workflow_call:
+    inputs:
+      wiki_dir:
+        description: "Directory, relative to the repository root, with the wiki pages"
+        type: string
+        default: "docs/wiki"
+      prune:
+        description: "true deletes wiki pages that are not in the folder; false keeps them"
+        type: string
+        default: "false"
+      tools-ref:
+        description: "Tag or branch of TirSystem/github-action whose tools/publish_wiki.py is run; pin it to the exact tag together with the workflow"
+        type: string
+        default: "v1"
+    secrets:
+      TOKEN_FOR_GITEA_WIKI:
+        description: "Gitea token with write access to the wiki of the calling repository"
+        required: true
+
+jobs:
+  publish-wiki:
+    permissions:
+      contents: read
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@v4.2.2
+
+      - name: Fetch the shared script
+        uses: actions/checkout@v4.2.2
+        with:
+          repository: TirSystem/github-action
+          ref: ${{ inputs.tools-ref }}
+          path: shared-scripts
+
+      - name: Publish the pages to the wiki
+        env:
+          GITEA_API_URL: ${{ gitea.api_url }}
+          SOURCE_REPOSITORY: ${{ gitea.repository }}
+          WIKI_CREDENTIALS: ${{ secrets.TOKEN_FOR_GITEA_WIKI }}
+          WIKI_DIR: ${{ inputs.wiki_dir }}
+          WIKI_PRUNE: ${{ inputs.prune }}
+        run: python3 shared-scripts/tools/publish_wiki.py