ci: GitLab-Pipeline - build_embedded + manueller npm-Publish nach rohana (threadnet-call#1)

Registry-Entscheidung evidenzbasiert: das Package ist pnpm-Dependency von
ThreadNet-Webs apps/web, der Lockfile pinnt die Tarball-URL auf rohana -
Registry bleibt dort. Publish-Auth ueber CI-Variable GITEA_NPM_TOKEN statt
lokaler Klartext-.npmrc.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/linking.md

@@ -0,0 +1,65 @@
+## Quickstart guide
+
+Run:
+
+```bash
+./scripts/setup-linking.sh
+```
+
+Read the script output:
+
+```
+Setup complete.
+Update: .links.cjs to your liking
+Run: 'pnpm links:on' to test your .links.cjs
+Run: 'git commit' with links enabled to test the git pre-commit hook.
+Run: 'pnpm links:off' to be able to commit again
+Run: 'git config --local core.hooksPath ""' to allow committing with linking (not recommended)
+Run: 'rm links.cjs' & 'git config --local core.hooksPath ""' to fully revert what this script did
+```
+
+# Developing with linked packages
+
+If you want to make changes to a package that Element Call depends on and see those changes applied in real time, you can create a link to a local copy of the package. `pnpm` has a command for this (`pnpm link`), but it's not recommended to use it as it ends up modifying package.json with details specific to your development environment.
+
+Instead, create a file named `.links.cjs` in the Element Call project directory (or run `./scripts/setup-linking.sh` to create a template), listing the names and paths of any dependencies you want to link. For example:
+
+```cjs
+// Packages to link to local checkouts
+module.exports = {
+  "matrix-js-sdk": "../your/path/matrix-js-sdk",
+  "matrix-widget-api": "../your/path/matrix-widget-api",
+};
+```
+
+Then run `pnpm links:on`. (this will activate the pnpm file + run `pnpm install` to setup the linking)
+
+## Hooks
+
+Changes in `.links.cjs` will also update `pnpm-lock.yaml` when `pnpm install` is executed. The lockfile will then contain the local
+version of the package which would not work on others dev setups or the github CI.
+
+One always needs to remove the pnpm `readPackage` script (the `.pnpmfile.cjs`) and run:
+
+```bash
+pnpm install
+```
+
+before committing a change.
+
+To make this less of a foot gun we added a git hook.
+A `pre-commit` hook will check if linking is currently used. If it detects
+a `.pnpmfile.cjs` file it will abort the commit with an explanatory message.
+You will then need to run `pnpm links:off` and commit again.
+
+To activate the hooks configure git with (when using the setup script (`./scripts/setup-linking.sh`) this is already done):
+
+```bash
+git config --local core.hooksPath .githooks
+```
+
+This will add the hook path for this repository only to .gihooks. which is a tracked (by git) folder containing the pre-commit hook.
+
+## Background
+
+Information, why this approach is used can be found in the [linking concept reasoning](./linking_concept_reasoning.md) document.