dashboard: the build pages are tabs of the dashboard

The build lifecycle used to be its own page with three sub-tabs. They are
now dashboard tabs (rebuild, meta, buildlogs) beside SW4RM and
P3RM1SS10NS: builds.js is a module tabs.js imports, so the dashboard's one
tab strip, /api/state snapshot and event stream (plus the meta_inputs_changed
and meta_update_running kinds) serve them, and the page, its bundle entry,
stylesheet and home tile are gone. The SW4RM banner's "view queue" link
points at the #rebuild tab, and the rebuild tab carries a count pill of the
rebuilds in flight.

An empty tab-count pill drew a "0": its display beat the UA [hidden] rule.

frontend/packages/shared/src/tabs/hive-tab-strip.js

@@ -1,5 +1,5 @@
 // hive-tab-strip.js — <hive-tab-strip>, the markup-owning tab-strip custom
-// element behind the logs/core/builds sub-page tabbars. Owns
+// element behind the logs/core sub-page tabbars. Owns
 // rendering the <a class="hive-tab"> markup from a declarative `tabs` list
 // instead of every page hand-writing the same <nav><a>...</a></nav>
 // boilerplate, then wires the existing createTabStrip() behaviour
@@ -21,7 +21,7 @@
 // — same id/aria-controls scheme the hand-written markup used, so each
 // page's panes (aria-labelledby="${prefix}-tab-${id}") don't need to
 // change. A `badgeId` tab also gets a nested `<span class="tab-count"
-// id="${badgeId}" hidden>` (matches builds.html's rebuild-queue count
+// id="${badgeId}" hidden>` (e.g. a rebuild-queue count
 // pill), then wires up createTabStrip() and returns exactly what it
 // returns ({ show, active }) — every existing `.active()`/`.show(id)`
 // call site keeps working unchanged. Call configure() exactly once per