fix(workspace-dropdown): move row paths from a second line to hover

[Harry19081]

Problem

Rows in the anchored workspace dropdown (the repo/workspace switcher on the
composer's SessionInfoLine) rendered their filesystem path on a second line.
useExternalRecentPaths sets description to the raw path, so every
"Used elsewhere" row printed one, and buildOpenPathItem did the same for the
open-path row.

DROPDOWN_CLASSES.item fixes the row at 32px (h-8 min-h-8), so a second line
overflowed the row and pushed the list past its LIST_MAX_HEIGHT. The row also
had no way to show a long path in full — the panel is 320px wide.

Solution

The path moves out of the row and into a framed side tooltip on hover. A new
RowDetailTooltip wraps any row that has secondary text; rows without it render
bare. RepoRow and OpenPathRow collapse to a single truncating label, matching
WorkspaceRow, which puts all three row types back inside the token-fixed 32px
height.

Placement is the load-bearing detail. Tooltip measures side placements from
the enclosing [role="menu"] panel and offsets by DROPDOWN_PANEL.submenuGap,
so the popup clears the panel border the same distance a submenu would. Without
that anchor the tooltip would be positioned against the row's inset rect and land
~2px inside the panel — and since .native-tooltip is z-1060 against the
panel's z-10000, that overlap would be occluded. The panel therefore gains
role="menu" and the rows role="menuitem", matching PortsStatusMenu
(the same search-panel shape) and AddActionsDropdown.

Two related token adoptions in the same file: the local VIEWPORT_MARGIN = 12
is replaced by DROPDOWN_PANEL.viewportPadding, and the removed second line
takes the arbitrary text-[11px] with it.

The tooltip carries the same content under the same condition as the old second
line — this relocates the information, it does not add or remove any.

Potential risks

• Discoverability. A path that was always visible is now behind a 200ms
  hover. That is the intended trade (it was overflowing its row), but a
  pointer-only affordance is worse for keyboard navigation: arrowing onto a row
  does not open the tooltip. Keyboard users can still tell rows apart by name,
  and the spotlight variant keeps its explicit "Show path" footer toggle.
• Positioning. If neither side fits the viewport, Tooltip clamps rather
  than flips and the popup can land over the panel, where the z-index gap hides
  it. smartPlacement is on, so this needs a viewport narrower than
  panel + tooltip on both sides.
• ARIA. role="menu" + role="menuitem" is a net improvement over buttons
  in a bare div, but getItemProps still sets aria-selected, which
  menuitem does not support. That attribute was already there (equally
  unsupported on a bare button), so this is pre-existing, not a regression;
  fixing it means touching the shared useDropdownListNavigation used by ten
  components.
• Not changed: LIST_MAX_HEIGHT (360) and MIN_DROPDOWN_WIDTH (320) keep
  their local constants. The nearest tokens are 200 and 280, so adopting them
  would resize the panel.

Verification

Run against this branch in an isolated worktree checked out at its own commit
(not the shared dirty checkout), with node_modules symlinked:

• npx tsc --noEmit --pretty false -p tsconfig.json — exit 0.
• npx vitest run --config config/vitest.config.ts src/scaffold/GlobalSpotlight
  — 28 files, 133 tests, all passing.
• npx eslint src/scaffold/GlobalSpotlight/palettes/WorkspacePalette/ — clean.
• npx prettier --check on the changed file — clean.
• npm run check:test-placement — clean (the directory colocates tests, and the
  new file is colocated).

New WorkspaceDropdown.test.ts covers the three behaviours: the row renders its
name only and not the path, hovering reveals the path in a tooltip and leaving
dismisses it, and the row resolves to a [role="menu"] ancestor so the tooltip
can clear the panel edge. Mutation-checked — restoring the second line, dropping
the tooltip, or removing role="menu" fails all three.

Not run / not applicable:

• No screenshots. ORG2 is a Tauri app with no browser-renderable entry
  point, so the dropdown cannot be captured without a full app launch. The
  hover behaviour is verified through jsdom rendering instead.
• E2E was not run; there is no rendered spec covering this dropdown.
• No "Pre-commit hook ran." trailer. The commit was built with plumbing
  (temp index + commit-tree) so the unrelated uncommitted work in the shared
  checkout could not enter it. Hooks were skipped, so typecheck, lint and tests
  were run by hand as listed above. Note the hook's TypeScript gate cannot fail
  a commit anyway (TSC_OUTPUT=$(...) || true then $? is always 0), so a green
  hook would not have been evidence.
• Base. Built on origin/develop (aa17dccd7). That commit's unused-export
  sweep (export interface WorkspaceDropdownProps to interface ...) is
  preserved rather than reverted — the local checkout predates it.