Build, publish to Gitea releases, and install the three extensions

Answers two things: how to install these without a marketplace, and how to keep
settings in sync when VS Code's Settings Sync cannot be pointed at Gitea.

- build.ps1 packages each extension into dist/
- publish.ps1 creates a release and uploads them, replacing same-named assets so a
  rolling "latest" tag stays clean
- install.ps1 downloads a release's assets and installs them, or -Local from dist/
- settings.ps1 copies User/ between the repo and the machine, and installs the
  marketplace extensions recorded in extensions.txt
- dev-link.ps1 junctions the sources into ~/.vscode/extensions for development
- ci-release.sh plus a Gitea Actions workflow do the build and publish on a tag push

Settings are copied, not symlinked: an atomic save replaces a symlink with a regular
file and the sync stops without looking broken.

vsce/ pins vsce and undici so packaging works on Node 18, which current vsce does not
support.

test/run.ps1 drives the real scripts against a stub of the Gitea release API. It
caught the multipart Content-Disposition being unquoted on .NET Framework, and
Invoke-WebRequest dropping the Authorization header across a redirect.

config.json

@@ -0,0 +1,26 @@
+{
+    "//": "Fill in your Gitea server. GITEA_URL / GITEA_OWNER / GITEA_REPO override these.",
+    "gitea": {
+        "url": "https://gitea.example.com",
+        "owner": "max",
+        "repo": "vscode-extensions"
+    },
+    "//extensions": "path is relative to this repo; repo is the Gitea repo to clone if path is missing.",
+    "extensions": [
+        {
+            "id": "colored-references",
+            "path": "../colored-references-src/colored-references",
+            "repo": "colored-references"
+        },
+        {
+            "id": "vertical-tabs",
+            "path": "../vertical-tabs",
+            "repo": "vertical-tabs"
+        },
+        {
+            "id": "dotnet-hot-reload",
+            "path": "../dotnet-hot-reload",
+            "repo": "dotnet-hot-reload"
+        }
+    ]
+}