deb: record per-phase build timings, shown by pkh deb profile

Time every Phase the build flow announces through enter_phase — the
chroot bootstrap (tarball download, extraction, finalization), the
apt phases, patch application, the build and binary steps and the
artifact retrieval — and land the ordered profile in the record's
manifest of every run, failed builds included: their profile ends
at the phase the error propagated out of.

Timing rides the enter_phase choke point instead of new measurement
sites, so a phase added later profiles itself. The manifest field
is additive (serde default, skipped when absent), so older manifests
keep loading without a schema bump. The coarse timings stay the
source of the deb list columns: they measure the apt transactions
themselves, where the profile measures whole phases.

pkh deb profile renders a record's profile through the same
read-only record discovery as pkh deb log — the newest record of
the tree, or an id prefix as shown by pkh deb list — so
record_for_log becomes the neutral find_record. Phase keys are
storage names, distinct from the display labels; Phase::from_key
turns them back and a test keeps both in sync.

src/test/bed.rs

@@ -11,6 +11,7 @@ use std::error::Error;
 use std::sync::Arc;
 
 use crate::context::Context;
+use crate::deb::BuildProfiler;
 use crate::deb::ephemeral::EphemeralContextGuard;
 use crate::report::BuildView;
 use crate::test::options::TestMode;
@@ -44,6 +45,7 @@ impl Bed {
                     None,
                     base_ctx,
                     view,
+                    &mut BuildProfiler::new(),
                 )
                 .await?;
                 Ok(Bed::Chroot(guard))

src/test/mod.rs

@@ -561,7 +561,8 @@ async fn configure_testbed(
     }
 
     if !opts.inject.is_empty() {
-        // Testbed setup is not a timed build: the durations go nowhere.
+        // Testbed setup is not a profiled build: the durations and the
+        // phase profile go nowhere.
         crate::deb::local::install_injected_packages(
             &opts.inject,
             env,
@@ -569,6 +570,7 @@ async fn configure_testbed(
             view,
             &None,
             &mut crate::deb::session::BuildTimings::default(),
+            &mut crate::deb::BuildProfiler::new(),
         )?;
     }
     Ok(())