new: add pkh put, a native dput replacement for PPA uploads

Upload built source packages over SFTP with host-key verification
(Launchpad fingerprints pinned in host_keys.yml, ask-to-accept
otherwise), Launchpad account discovery (git config lp.user), and
pre-flight checks the upload queue itself never does: changes file
discovery/validation, PPA existence via the Launchpad API, target
series validity, and debian/control Section validity (sections
bundled in distro_info.yml). Upload log prevents duplicate uploads
unless --force.

src/main.rs

@@ -164,6 +164,13 @@ fn main() {
                 .about("Build the source package (into a .dsc)")
                 .arg(arg!(--verbose "Show raw tool output instead of the live build view").required(false)),
         )
+        .subcommand(
+            Command::new("put")
+                .about("Upload the built source package to a PPA")
+                .arg(arg!(--ppa <ppa> "Upload to a PPA (format: user/ppa_name)"))
+                .arg(arg!([changes] "Explicit .changes file to upload (default: the one built from this package, next to the source tree)").required(false))
+                .arg(arg!(--force "Upload even if this exact .changes file was already uploaded to the target")),
+        )
         .subcommand(
             Command::new("deb")
                 .about("Build the source package into binary package (.deb)")
@@ -470,6 +477,37 @@ fn main() {
                 std::process::exit(1);
             }
         }
+        Some(("put", sub_matches)) => {
+            let cwd = current_dir_or_exit();
+            let ppa = sub_matches.get_one::<String>("ppa").map(|s| s.as_str());
+            let changes = sub_matches
+                .get_one::<String>("changes")
+                .map(std::path::PathBuf::from);
+            let force = sub_matches
+                .get_one::<bool>("force")
+                .copied()
+                .unwrap_or(false);
+
+            // Only PPA targets are implemented for now
+            let Some(ppa) = ppa else {
+                error!(
+                    "pkh put needs a target: pass --ppa user/ppa_name \
+                     (archive uploads are not supported yet)"
+                );
+                std::process::exit(1);
+            };
+
+            let options = pkh::put::PutOptions {
+                ppa: ppa.to_string(),
+                changes,
+                force,
+                cwd,
+            };
+            if let Err(e) = rt.block_on(async { pkh::put::put(&options, &multi).await }) {
+                error!("{}", e);
+                std::process::exit(1);
+            }
+        }
         Some(("deb", sub_matches)) => {
             let cwd = current_dir_or_exit();
             let series = sub_matches.get_one::<String>("series").map(|s| s.as_str());