A single deferred scroll computed against an un-settled layout strands
the cursor when images / nested mounts continue reflowing after the
triggering action — the "still found cases where the active node
selection isn't revealed" case on #291.

Node selection (__scroll_node_cursor_into_view):
- IntersectionObserver on the two nodes flanking the cursor gap re-fires
  the scroll on each viewport-edge crossing, until the selection moves
  on, the user scrolls (after a 500ms grace so the settling relayout
  and any inertial scroll can't abort it), or a 2s safety timeout fires.
  Replaces the rAF-poll-until-deadline loop with an event-driven watch
  that catches relayout shifts past the first visibility-pass.

Property and text selection:
- setTimeout(fn, 0) -> await tick() then a rAF (with 50ms fallback for
  background-tab rAF throttling). tick() drains Svelte's effect queue
  so the scroll measures the post-flush DOM, not the pre-flush one.
- Job-id cancellation so a fresh render invalidates an older pending
  scroll instead of letting both yank the viewport.
- Text selection captures focusNode.parentElement at run time, not at
  enqueue time, so a focus that moves during the settle window doesn't
  scroll a stale element.

Node-cursor watch starts also bump the property/text job-id, so a node
render cancels any pending property/text scroll scheduled just before
it.

Adopts the deferred-scroll helper shape from #292 for the property/text
generalization; #292 can be closed in favour of this combined approach.
svedit-lab "Run Smoke Tests": 25/25 pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

A single deferred scroll computed against an un-settled layout strands
the cursor when images / nested mounts continue reflowing after the
triggering action — the "still found cases where the active node
selection isn't revealed" case on #291.

Node selection (__scroll_node_cursor_into_view):
- IntersectionObserver on the two nodes flanking the cursor gap re-fires
  the scroll on each viewport-edge crossing, until the selection moves
  on, the user scrolls (after a 500ms grace so the settling relayout
  and any inertial scroll can't abort it), or a 2s safety timeout fires.
  Replaces the rAF-poll-until-deadline loop with an event-driven watch
  that catches relayout shifts past the first visibility-pass.

Property and text selection:
- setTimeout(fn, 0) -> await tick() then a rAF (with 50ms fallback for
  background-tab rAF throttling). tick() drains Svelte's effect queue
  so the scroll measures the post-flush DOM, not the pre-flush one.
- Job-id cancellation so a fresh render invalidates an older pending
  scroll instead of letting both yank the viewport.
- Text selection captures focusNode.parentElement at run time, not at
  enqueue time, so a focus that moves during the settle window doesn't
  scroll a stale element.

Node-cursor watch starts also bump the property/text job-id, so a node
render cancels any pending property/text scroll scheduled just before
it.

Adopts the deferred-scroll helper shape from #292 for the property/text
generalization; #292 can be closed in favour of this combined approach.
svedit-lab "Run Smoke Tests": 25/25 pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>