Damocles's backend (c41bf1b) landed HYPERHIVE_HIVE_NAME / _SWARM_NAME
env vars and identity.rs accessors. This commit wires them into the two
web surfaces:
hive-c0re/dashboard.rs:
StateSnapshot gains `hive_name` + `swarm_name` (Option<String>),
populated from the env vars the c0re NixOS module injects.
hive-ag3nt/web_ui.rs:
Per-agent StateSnapshot gains the same two fields, populated from
crate::identity::hive_name() / swarm_name().
Dashboard frontend (index.html + tabs.js):
A `<p class="banner-thin" id="hive-identity">` sits above the tab
strip in the chrome. refreshState() populates it with "swarm / hive"
(or just "hive") when the fields are non-null, and updates
document.title to "<swarm>/<hive> // h1ve-c0re". No change to
chrome when both fields are null (backward compat).
Per-agent frontend (index.html + app.js + agent.css):
A hidden `.agent-hive-label` span under the title row shows the
swarm/hive label once setHeader() receives non-null names.
document.title is updated to "<label> // <hive_name>" when hive_name
is set, enabling browser-tab disambiguation when multiple hives are
open in parallel. Styled as a small uppercase purple-dim sub-label.