feat: Neuroglancer Views polish (PR 7, ngviews-07-cart-and-viewer-polish) - #431

Drop the redundant h6 title (already shown in the breadcrumb) and move
the action buttons up to the breadcrumb row. Frees vertical space for
the Neuroglancer iframe.

…ontal scroll

- Fix the missing 6th grid track so the Actions cell stops wrapping to a
  second row on each entry.
- Add an optional gridColsStyle prop on TableCard (inline
  gridTemplateColumns, alt to the static gridColsClass), since Tailwind
  JIT can't emit arbitrary-width classes at runtime.
- The Sources column has its own drag handle at the column's right edge
  (thin line, primary color on hover/drag). Sources cell now shows each
  source path on a truncated line with a native tooltip on hover, so long
  paths stay clickable and inspectable without eating the whole row.
- Wrap the header + body in overflow-x-auto so widening Sources doesn't
  push the trailing columns off-screen unreachable.
- Explicit left-align across every cell (justify-start + text-left).

…idebar

… layer

…)" to "View(s)"

…restore QueryClient-free rendering

… empty scales

The Sources column showed each layer's path relative to its file share,
which is ambiguous across shares. Resolve the FileSharePath from the
layer's fsp_name and render the full path (share path plus subpath)
using the viewer's path-format preference, matching how the Data Links
and Jobs tables display paths. Fall back to the relative path when the
share can't be resolved, such as a local environment with no central
URL configured.

…cart

Expanding a plain (non-OME) Zarr array in the Layer Cart showed an empty
body: it has no multiscale axes to fill the dimension table and no
channels to select, so the row looked broken. Show "No OME-Zarr metadata
to display" when a dataset has neither axes nor channels. OME datasets
keep the axis table and channel checkboxes unchanged.

The default column tracks summed to 1040px, forcing a horizontal
scrollbar the first time the Views page loads. Narrow the Name and
Sources columns and tighten the Sharing, Updated, and Actions tracks so
the default layout fits. Name truncates with a tooltip, and Sources
stays resizable for long paths.

The new "Create a view of this dataset" viewer icon's aria-label
contains "Create", so the broad page-wide button locator
/confirm|create|yes/i now matches it alongside the actual dialog
confirm button, causing a strict-mode violation. Scope the locators
to the open dialog to disambiguate.

The Views work added a "Create a view of this dataset" button to the
zarr metadata preview. Its accessible name matches the page-wide
/confirm|create|yes/ locator these tests used for the data-link
confirmation button, so Playwright's strict mode failed on two matching
elements. This passed locally against a stale bundle without the button
and failed only in CI, which builds fresh.

Scope the locator to the dialog, matching the pattern already used in
data-link-operations.spec.ts, so the preview button no longer collides.

The viewer route rendered the full app navbar above the iframe,
duplicating chrome and wasting vertical space. Suppress the global
navbar on /view/:readKey and give NeuroglancerView its own collapsed
bar with the logo, profile menu, and tooltipped icon buttons instead
of labeled buttons.

Move the theme toggle and GitHub link out of the navbar and into
ProfileMenu (GitHub also gets a Help-page entry) so both the main
navbar and the viewer's bar share one menu. Extract LogoSvg to its
own file so it's reusable outside Navbar.tsx, and read/restore the
theme in MainLayout (always mounted) instead of Navbar so dark mode
still applies on routes that hide the navbar.