report,ui: name the tee log by flow kind

BuildTarget::source_only carried two states for what is a three-way
distinction now that pkh test exists: replace it with a TargetKind
(Source/Binary/Test) and derive the tee log prefix (build-/deb-/test-)
from it, so test runs get their own log family instead of borrowing
the deb one.

src/report.rs

@@ -28,6 +28,18 @@ use crate::logfmt::Classifier;
 /// why it is rejected (the implementation re-asks with the explanation).
 pub type Validator = dyn Fn(&str) -> Result<(), String>;
 
+/// Which flow a target belongs to; names the terminal adapter's tee log
+/// (`build-*.log`, `deb-*.log`, `test-*.log`).
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum TargetKind {
+    /// Source-only build (produces a `.dsc`).
+    Source,
+    /// Binary build (produces `.debs`).
+    Binary,
+    /// DEP-8 test run (`pkh test`).
+    Test,
+}
+
 /// Identity of the build whose events follow, as announced through
 /// [`BuildView::target`].
 #[derive(Debug, Clone)]
@@ -45,9 +57,8 @@ pub struct BuildTarget<'a> {
     /// "Uploading hello (2.10-3) to ppa:user/ppa"): the wording is the
     /// flow's, adapters render it verbatim.
     pub display: String,
-    /// Whether this is a source-only build (producing a `.dsc`); names the
-    /// terminal adapter's tee log (`build-*.log` vs `deb-*.log`).
-    pub source_only: bool,
+    /// The flow driving the events; names the terminal adapter's tee log.
+    pub kind: TargetKind,
     /// Whether the view should tee raw subprocess output to its log file.
     /// Flows without subprocess output (uploads) pass `false` and create
     /// no log file.