new: port the rust template bodies to manifests

data/templates/rust/Cargo.toml.tpl

@@ -0,0 +1,6 @@
+[package]
+name = "{crate_name}"
+version = "{upstream_version}"
+edition = "2021"
+
+[dependencies]

data/templates/rust/main.rs.tpl

@@ -0,0 +1,4 @@
+// Placeholder for {name}, generated by `pkh new`.
+fn main() {
+	println!("Hello from {command}!");
+}

data/templates/rust/manifest.yml

@@ -1,8 +1,11 @@
 ## The `rust` template: a vendored Cargo build (see the module docs of
-## src/new/templates/rust.rs for the vendoring strategy). The logic half —
-## the cargo vendor post-write hook, the Cargo.toml/src skeletons with
-## their crate-name sanitizing, and the `{locked}` / `{artifact}` values of
-## rules.extra.tpl — lives in that module.
+## src/new/templates/rust.rs for the vendoring strategy). The skeleton
+## bodies and the vendored-build rules overrides below are static data; the
+## logic half — the cargo vendor post-write hook, the project probe, and
+## the `{crate_name}` / `{locked}` / `{artifact}` values of the bodies —
+## lives in that module (dpkg package names may carry `+`/`.`, which cargo
+## rejects in crate names, so the skeleton crate name is a derived
+## placeholder, not the raw `{name}`).
 ##
 ## Schema: see src/new/templates/mod.rs.
 
@@ -23,4 +26,8 @@ rules_extra_file: rules.extra.tpl
 gitignore_entries:
   - vendor/
   - .cargo/config.toml
-files: []
+files:
+  - path: Cargo.toml
+    template: Cargo.toml.tpl
+  - path: src/main.rs
+    template: main.rs.tpl