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>
