report: reproduce the pre-refactor CLI output through the ports

Instead of carrying raw UI in core, the ports now represent everything
the CLI used to do inline:

- Prompter::present shows context outside of a question (the wizard
  summary screen, the vendoring notice spacing); TerminalPrompter
  prints it on stdout exactly like the println!s it replaces, server
  embeds forward it as a display event.
- generate_entry returns the generated entry (package, versions,
  series, path) instead of printing; the CLI renders the same lines.
- BuildTarget carries a flow-composed display line and a tee_log flag:
  the terminal adapter renders it verbatim ("Building source package
  ...", "Building ... for series/arch", "Uploading ... to ...") and
  uploads open no build log.
- The unmet build-dependency diagnostics are rendered by the CLI from
  the typed error, in the original order (details, then summary).
- --verbose constructs no live view at all (an idle widget used to
  linger), and the re-vendor offer only logs when it is actually
  asked, so headless runs print the error exactly once.

src/build/mod.rs

@@ -169,6 +169,13 @@ fn retry_after_revendor(
     opts: &SourceBuildOptions,
     original: Box<dyn Error>,
 ) -> Result<SourceBuildOutput, Box<dyn Error>> {
+    // The offer is only made when someone can answer it: headless prompters
+    // answer with the default (false) without the error being logged here —
+    // the caller logs the returned error itself, exactly once.
+    if !prompter.interactive() {
+        view.finish_failure();
+        return Err(original);
+    }
     log::error!("{original}");
     if !prompter
         .confirm(
@@ -301,7 +308,14 @@ pub fn run_source_build(
         package: &entry.source,
         version: &entry.version.full(),
         target: &entry.distribution,
+        display: format!(
+            "Building source package {} ({}) for {}",
+            entry.source,
+            entry.version.full(),
+            entry.distribution
+        ),
         source_only: true,
+        tee_log: true,
     });
 
     let source_display = entry.source.clone();
@@ -389,9 +403,9 @@ pub fn run_source_build(
         };
         let report = crate::debian::deps::check_build_depends(&ctrl, &check_opts)?;
         if !report.is_ok() {
-            // The diagnostics travel inside the error (its Display carries
-            // report.message()); main renders it and maps the type to exit
-            // status 3, like dpkg-buildpackage.
+            // The typed error carries the diagnostics (UnmetReport is
+            // public); the caller renders them and maps the type to exit
+            // status 3, like dpkg-buildpackage does.
             return Err(Box::new(crate::debian::deps::UnmetBuildDependencies(
                 report,
             )));