Pure structural move, no API or behaviour change: tabs.js/tabs.css
move into shared/src/tabs/, matching the one-dir-per-component
layout the other shared components already use (hive-btn,
hive-dialog, hive-toast, hive-menu, side-panel).
Both files are consumed exclusively through @hive/shared's
package.json exports map (./tabs.js, ./tabs.css), never by a raw
relative path, so updating the two export targets is the only
change needed -- none of the 9 call sites (dashboard tabbar, logs,
core, builds, credentials, stats x2, agent stats) touch anything.
Verified the built dashboard/agent bundles still resolve both
files correctly.
Adds @hive/shared/tabs.js — createTabStrip(tabbar, {defaultId, onShow}):
a hash-routed tab strip that resolves controls by `[data-tab="<id>"]`
inside the passed container and panels by `[data-tab-pane="<id>"]`,
toggling `.hive-tab--active` + aria-selected + the panel's `hidden`, and
firing onShow(id) for per-tab side-effects. Always hash-routed (deep-
linkable + back/forward), no element-resolver callbacks (convention over
config), per the #1464 design review.
Wires it up: @hive/shared exports `./tabs.js` + `./tabs.css`, and
common.css @imports tabs.css (component structure, not a swap target, so
inlining is fine — unlike theme.css).
Migrates the logs sub-tabs as the first consumer: markup uses
`.hive-tab`/`data-tab`/`data-tab-pane`, logs.css drops the duplicated
base styles (keeps only its `flex:1` layout delta), and logs.js swaps its
activeTab/showTab/hashchange for createTabStrip (onShow lazy-loads the
SYSTEM tab). Behaviour-preserving. aria-selected is now standardised.
