Product repository template

Layout, proplan.toml, README/CHANGELOG, placeholder product image, .gitignore, KiBot/release/docgen workflows and TEMPLATE.md. Source of truth: contrib/product-template in B4L/proplan (cargo test --test product_template checks it as Gitea 1.27 creates a repository from it).

proplan.toml

@@ -0,0 +1,24 @@
+# proplan.toml: what proplan reads from this repository. The Code tab shows
+# whether the folders named here exist, the product image appears on the
+# project and on each prototype stage. Every key is optional; an omitted path
+# means the folder of the same name. TEMPLATE.md has the full reference.
+schema = 1
+
+[product]
+name = "$REPO_NAME"
+image = "assets/product.png"
+
+# One entry per KiCad project. A real variant (48 V, 2-board) is another
+# entry with its own folder; a revision is a git tag, never a folder copy.
+[[boards]]
+name = "$REPO_NAME"
+path = "hardware/$REPO_NAME"
+
+[paths]
+firmware = "firmware"
+software = "software"
+mech = "mech"
+sim = "sim"
+test = "test"
+docs = "docs"
+external = "external"