feat(web): add in-thread find#7434

fix(web): reopen thread find with match shortcuts

fix(web): align find toggle and reveal matches

fix(web): right-anchor responsive find bar

fix(web): keep thread find bar responsive

fix(web): use shared toggle for match case

fix(web): emphasize match case state

fix(web): refine thread find controls

feat(web): add match-case thread search

fix(web): refine in-thread find behavior

fix(web): clamp active find match

fix(web): keep find overlay elevation stable

fix(web): make find overlay opaque in dark mode

Merge branch 'main' into codex/find-in-thread

fix(web): let find input own its surface

fix(web): highlight matches across markdown nodes

Merge branch 'main' into codex/find-in-thread

fix(web): align find matches with rendered text

fix(web): address in-thread find feedback

feat(web): add in-thread find