Adds the P33RS tab to the dashboard. The tab is hidden by default and
only shown when at least one peer hive is configured in
`services.hyperhive.peers`. When visible, it renders a card per peer
with a link to that hive's dashboard.
Backend (HYPERHIVE_PEERS env var, PeerHiveView in StateSnapshot) is
wired by a separate PR. This commit is frontend only:
- index.html: P33RS tab strip entry + tab-pane-peers section
- tabs.js: renderPeerHives(), gate logic, 'peers' added to TABS array
7a8b8fe266