The visible declaration already provides scope context. Cache the actual
identifier point separately from the declaration extent/decorators and hide
labels when it is visible in that side of the projected viewport.
Refill reclaimed rows and anchor carets against the resulting layout.
Retain sticky context when the symbol scrolls or wraps out of view.
Verified: 951 tests passed, cargo build, and real PTY smoke for declaration
visibility/scroll restoration, wrapping, horizontal clipping, unified view,
and short horizontal-pane caret reflow.
Valdemar Lorenzen
a93afc7d16