* feat(web): reveal a clipped sidebar session title on hover
A session title wider than its sidebar row is clipped with an ellipsis, so a
long parent title hides the `(1)` that distinguishes its fork. Hovering the row
now scrolls the title to its far edge and returns it to the start when the
pointer leaves. The title stays an `overflow: hidden` scrollport, so nothing
reflows and no scrollbar appears; `scroll-behavior: smooth` supplies the motion
(reduced motion keeps the jump), and the hovered row clips instead of
ellipsizing because a scrolled box still paints the ellipsis over the revealed
characters.
Covered by the row component spec, the stylesheet contract spec, and a new
keyless Chromium scenario that hovers a seeded clipped row in the assembled
application and asserts the reached scroll extent.
* fix(web): return the revealed session title in one step
Review follow-up on the hover reveal:
- Return the title to its start with `scrollTo({ behavior: 'instant' })` instead
of a smooth scroll. A smooth return carried the resting ellipsis and the
narrowing cell over the travelling text for its whole duration.
- Scope `scroll-behavior: smooth` to `.sessionRow .title` so Workspace rows are
untouched, and fold the reduced-motion reset into the file's existing block.
- Guard the hover-only `text-overflow: clip` with `@media (hover: hover)`: a
touch tap latches `:hover` after the title has already returned, which would
otherwise strand that row without its ellipsis.
- Pin the contract in the browser scenario: computed `scroll-behavior` is
`smooth` by default and `auto` under reduced motion, and the return lands
inside one step. Add the unit case for the explicit instant return.
A collapsed plugin card carried both an enablement tag and a green root-fiber
status dot; for the common `active` phase the two stated the same settled
state. The dot now renders only for `pending`, `loading` and `unloading`,
the phases the enablement tag cannot state, and the expanded card keeps the
phase fact.
Related to #4424
zhc