Generic host/repo/branch-aware CD on adnanh/webhook

Replaces the per-project deploy scripts and self-contained webhook
receivers with one manifest-driven implementation that lives outside the
application repositories and can be updated independently of them.

First targets: domaindingo test and prod on s5.

.github/copilot-instructions.md

@@ -0,0 +1,12 @@
+# Agent instructions
+
+This project's knowledge base lives in `ai-context/` and `docs/`. **Do not read
+it preemptively.** When a task may touch project infrastructure, services, or
+repository operations, consult the routing index `docs/active-context.md` and
+open an entry only if its trigger matches your task.
+
+Files under `ai-context/` are read-only — the install script overwrites them on
+update, so local edits are lost.
+
+Record project-specific discoveries (gotchas, quirks, non-obvious tool
+behaviour) as short entries in `docs/hints.md`; prune stale ones.