[laksamanakeris]

Wires the studio chrome to the seam: rail badges, breadcrumb, statusbar, database picker, and the palette's connection list. Every shortcut moves to one handler at the app root. Still 100% mock.

Size	16 commits, 24 files, +680 / −252, 1 new file
Tests	261 → 276
Gate	fmt, clippy -D warnings, nextest, all clean
Checked in the app	Rail badges. Breadcrumb across Explorer, Streams and back. Statusbar version and timezone. Database lists for local (3) and staging (12). Palette switch targets on local and on prod. READ-ONLY pill on prod. ⌘K, ⌘D, ⌘, and Esc while connected, while disconnected, inside a modal, and after Esc from a modal input.
Risk	Seam model change: SessionInfo loses database, role and read_only, and ActiveConnection loses databases. The compiler flags every site. The palette and popover signals move from Studio to App.

The design choice to accept or reject

Each session fact has one owner.

Before this PR, role and current database lived on both ActiveConnection and SessionInfo. The database list lived on both ActiveConnection.databases and databases(). The mock had already drifted: databases() returned 5 names, and local's profile lists 3.

Now:

• ActiveConnection owns identity, capabilities, role and current database. They come from the connect result.
• session_info() owns server version and timezone, the facts the connect result does not carry.
• databases() owns the database list. The mock answers for the session the last connect opened, and returns NotConnected before one.

If the real client learns the role or database from a session query instead of the connect result, the owner moves to session_info(). Say so here if you know it does.

Where to spend review time

1. app.rs, one key handler and focus. A key reaches a handler only from a focused element inside it. A click focuses the nearest focusable ancestor. ⌘, and Esc sat on the app root, and ⌘K and ⌘D on the studio's .app. A click inside a modal focused the root, so ⌘K then did nothing.

Now every key is handled on the root, and the palette and popover signals live in App. The root takes focus back when the modal and palette close, and on disconnect. Esc from a modal input unmounted the focused element and dropped focus to <body>, outside every handler.

Guards:

• ⌘K and ⌘D act only while connected.
• ⌘, does nothing while a modal is open. Replacing the modal discarded its typed fields.
• Keys pressed while an IME composes text are ignored, so Esc cancels the candidate, not the modal. Untested with a real IME. It is unconfirmed whether WebKit sets isComposing on that Esc.

2. Per-connection re-reads. The notification feed, rail badges, statusbar, sidebar and database list re-read when the connection changes. They subscribe to a memo of the connection name that App provides, not to active. A database pick or a failed switch also writes active, and neither changes what the server answers.

resource_state reads a pending re-run as Loading. Resource::read keeps the previous result until the new one lands, so right after a switch the chrome showed the last server's values. The mock answers at once, so no test covers that case.

App also built a new mock on every render. use_resource re-runs with the latest render's closure, so the feed reload read fresh mock state. A database pick brought back every notification the user had marked read. The backend is now built once.

3. Explorer selection, now in state/explorer.rs. It moves from the Explorer view to Studio, so the topbar breadcrumb can read it. A switch clears it, and the Explorer picks the new server's default. A collection with the same name on another server can have another storage mode, and the old pick kept the old viewer.

One thing I want your call on

Does a NodeDB session have a current database? The picker lists databases(), and a pick updates the chip and statusbar. Nothing reaches the server. No seam method switches the session's database, and collection_groups() takes no database. With a real client, the Explorer keeps listing the session database's collections under the picked name.

Options:

• Sessions have a current database: add a use_database(name) seam method.
• They do not: add a database argument to the per-database reads.
• Neither is settled yet: disable the picker until one is.

The sidebar no longer re-reads on a pick, because the re-read returned the same set.

Smaller changes

• Route::required_cap is an exhaustive match. A new route must state whether it is gated.
• Breadcrumb labels follow the mockup. The Explorer appends the selected collection. The database is not in it, because the database chip shows it. An unknown Streams tab reads as CDC, the screen the Streams view renders for it.
• Breadcrumb spans key by position, because a crumb's position is its level. data_grid.rs keys its columns the same way.
• Rail badges hide on zero, while loading, and on a failed read. A count there is a number this server never sent.
• The statusbar shows "session info unavailable" on a failed read, with the error in its tooltip. The mockup's "last query" latency is not shown: nothing produces one until the Query workbench runs through the seam.
• The READ-ONLY pill was never visible. The stylesheet hid it unless <body> carried a readonly class, which the mockup's JS set and nothing in the app sets. The topbar renders the pill only for a read-only connection, so the CSS gate is gone.
• The palette's Connections section comes from the registry: every reachable saved connection except the current one. It listed two hardcoded names before.
• SavedConnection::credentials replaces three inline copies of the profile-to-credentials rule.