dashboard: queue log link opens BUILD L0GS tab instead of downloading

Fixes hyperhive#2895. The rebuild-queue tree's per-node log icon (the
printer-glyph "open" affordance next to each node in the R3BU1LD
QU3U3 tab) linked directly to the raw-text download endpoint
(/api/build-log/<node_id>/raw, which sets Content-Disposition:
attachment server-side) -- surprising, since nothing about that icon
signals "this leaves the app", unlike the other two explicit
"download raw"/"raw" links elsewhere on the page.

Point it at the existing ?id=N#buildlogs deep-link into the BUILD
L0GS tab instead (builds.js's fetchBuild already auto-expands +
scrolls to the matching row there). That deep-link's id is the
build-log history row id -- a different id space than the queue
tree's NodeId, and wasn't exposed to the frontend before (only a
derived has_log bool was). Added NodeView.build_log_id: Option<i64>
to the wire type alongside the existing has_log (kept, since
findLiveBuild's separate live-log-panel gate still needs a plain
bool), threaded through job_queue::mod.rs, updated hivectl's NodeView
test-helper literal.

The raw download is still one click away once on that row's BUILD
L0GS detail (the two already-explicit raw-download links are
untouched). cargo build/clippy/test clean across the three touched
crates (hive-c0re, hive-host-sock, hivectl); nix fmt clean; frontend
build verified (grep for build_log_id in the built builds.js bundle).

hivectl/src/dag_progress.rs

@@ -343,6 +343,7 @@ mod tests {
             approval_id: None,
             inputs: vec![],
             has_log: false,
+            build_log_id: None,
         }
     }