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.
fbc09f1b3d