fix(record): recover CSS rules when another script displaces the insertRule patch

[Vadman97]

CSS-in-JS rules only reached the replayer via the CSSStyleSheet.prototype.insertRule patch, so any script that reinstalls a previously captured insertRule silently unhooks recording and the replay freezes with the CSS that existed at snapshot time. Recording now probes that its patch still runs, reinstalls it over whatever displaced it, re-sends the missing rules, and on teardown only unwinds its own layer.

Found while investigating a production session that kept 734 of 2929 emotion rules and replayed a MUI-heavy modal completely unstyled.

  - End-to-end against the real session with the published player: injecting the events the fix would emit took the emotion sheet from 734 → 2929 rules and made .css-df1p9r/.css-q679rt/.css-wqv4tk resolve; at session start it took the sheet 32 → 614 rules
  and #programsTable from 998×3277 (broken) to 1080×700 — the same geometry as the healthy render. Modal classes with no rule went 47 → 15, the residual only because I borrowed rule text from a later page load that lacks that load's styled-components
  hashes.

🤖 Generated with Claude Code

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Note

Overview
When another script restores a captured CSSStyleSheet.prototype.insertRule, CSS-in-JS runtime rules stop reaching the recording and replay stays stuck at snapshot-time CSS. Recording now periodically probes whether its patches still run (via a throwaway constructed stylesheet), reinstalls displaced insertRule/deleteRule proxies over whatever is on the prototype, and re-emits missing rules as normal StyleSheetRule events.

The new styleSheetResyncInterval record option controls that interval (default 2000 ms; 0 disables). Teardown uses restorePatchedMethod so only rrweb’s layer is removed—stopping the recorder no longer strips another vendor’s wrapper; proxies that remain in the chain go silent via a stopped flag, with re-entrancy guards so chained self-repatches do not double-report rules.

Puppeteer tests cover displacement, repatch, no duplicate resync, partial displacement, cooperative wrappers, and teardown behavior.

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[RobertPakkoLD]

I would resolve the bugbot comments, but general approach seems fine to me.