feat(studio): operator-mode pass — Store + audit detail + channel switcher (v0.10.0)

Turns Studio from read-only dashboard into operator console.
Pieces:

  * **New Store page** (sidebar destination #3): browses the
    hub's bundled store-index with query + category + status
    filters. Each card has an Install button that prompts for
    the `.fai` bundle source (URL or local path), ships it to
    HubAdmin.InstallModule, shows success / error in a progress
    dialog, refreshes the list.

  * **Audit drill-down**: every event row is now tappable;
    opens a modal with all LoggedEvent fields including the
    new `detail` JSON pretty-printed in a code block. KRITIS
    forensic story: every audit row → full structured detail
    in two clicks.

  * **Approvals payload preview**: shipped already; now
    pretty-prints JSON when the preview parses as such, plus
    a clearer `PAYLOAD PREVIEW` label. Reviewer identity
    defaults to `$USER@studio` instead of the hard-coded
    `studio-mvp` so the audit trail records who acted.

  * **Channel switcher in Settings dialog**: the dialog now
    pulls HubAdmin.ChannelStatus and renders one row per
    channel (local / dev / beta / production) with port,
    running indicator, active marker. A "Connect" button
    on a running channel sets Studio's endpoint to that
    channel's port and reconnects in one click.

Cmd+1..6 keyboard shortcuts updated for the six destinations.
Widget test asserts every destination renders.

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

pubspec.lock

@@ -79,7 +79,7 @@ packages:
       path: "../fai_dart_sdk"
       relative: true
     source: path
-    version: "0.2.0"
+    version: "0.3.0"
   fake_async:
     dependency: transitive
     description: