feat(store,doctor): surface the hub's trust + exposure data (0.77.0)

The trust-gate dialog replaces its generic 'no per-entry status yet
(alpha)' note with the hub's classified verification statement —
pinned store key / trusted publishers (green), installs without
signature checking (amber), install would be refused (red), bridge
entry (neutral) — via one shared describeInstallVerification mapping.
Against a pre-0.23 hub the field is empty and the old honest wording
stays (pinned by test).

Information architecture: policy-off is a GLOBAL fact, so it appears
as ONE ChainInlineHelp notice above the store grid instead of a
warning pill on every card (card noise); only 'blocked' — a genuine
per-source anomaly — earns a card pill. Doctor's host services show
the hub-classified network reach per endpoint (local only / private
network / publicly reachable with a protect-it hint / reach unknown).

Verified end-to-end against the live dev hub (guide harness): the
wire field arrives, the store page shows exactly one policy notice
and quiet cards; trust-gate variants captured via the dialog
harness. Suite 123 green.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

pubspec.yaml

@@ -1,7 +1,7 @@
 name: chain_studio
 description: "Ch∆In Studio — desktop GUI for the Ch∆In hub"
 publish_to: 'none'
-version: 0.76.0
+version: 0.77.0
 
 environment:
   sdk: ^3.11.0-200.1.beta