[codex] Fix OSC 8 hyperlink state transitions (#1112)

* fix: hyperlink URL state transitions (fixes #1100)

* test hyperlink empty state coverage

revert: "refactor(simscreen): reuse drawCell encode buffers"

reverts 1ccc145. the lift moved 12-byte scratch buffers from per-call
make to simscreen fields. measured impact varies by escape decision:
in escape-forced callers (gitgum) it saves ~14% allocs, but in the
standalone benchmark the original was already stack-allocated, and
the indirection through the struct field measurably regresses Show
time by 2-8%. dropping in favour of keeping the PR scoped to wins
that are unambiguous on the standalone bench.

Sanitize OSC 8 links (fixes #1061)

fix: backport OSC 8 sanitizer to v2

Move away from uniseg to faster clipperhouse/displaywidth

Use an intern string cache to reduce allocations.

This has improved correctness, and substantial performance improvements.

fix(tty): flush input before start (fixes #1045)

fix(tscreen): Last column snafu with workaround for wide characters.

The hack to fix #976 caused another problem where the wide characters
didn't render properly on the last column as the backspace did not
go backwards with pending wrap state.  (This might actually be considered
a terminal bug as well.)

We don't use the work around at the right edge of the screen.  This may
mean that buggy terminals will still see screwy behavior in the far
right column, but at least it will be fixed everywhere else.

fix(tscreen): Last column snafu with workaround for wide characters.

The hack to fix #976 caused another problem where the wide characters
didn't render properly on the last column as the backspace did not
go backwards with pending wrap state.  (This might actually be considered
a terminal bug as well.)

We don't use the work around at the right edge of the screen.  This may
mean that buggy terminals will still see screwy behavior in the far
right column, but at least it will be fixed everywhere else.

(cherry picked from commit 49eaa4d)

fix: fix for wide not overwriting adjacent character (fixes #976)

This is a workaround - and really if it this is happening it means that
your terminal emulator is a bug.  I'm not sure I want to merge this.

I have not observed the behavior that this change is meant to fix.

fix: fix for wide not overwriting adjacent character (fixes #976)