test: fix the UI flows that fail on main

[datlechin]

Why

• 12 of the 47 UI flows from test: rewrite the test suite, test plans and CI #3412 fail on main. They had never run before that PR's CI.
• Return in Switch Connection reopened the current connection after typing another one's name, when a file path matched the query.

Change

• The grid helper reads the cell's value view, not its empty wrapper (7 flows).
• Inspector, first-table-load, structure-drop, appearance-scroll and import-review flows match what the runner shows.
• The switcher selects the best match for a new query, with a unit test.

Verified

• Diagnosed from the failed run's recordings and element trees. The UI target builds; this PR's CI is the first run of the fixed flows.

Not in this PR

• The collapsed one-tab editor strip still publishes to accessibility.
• The structure editor overflows a 1024 pt window.