fix: reuse parser WeakRef for timeout callbacks

[trivikr]

This relates to...

N/A

Rationale

Parser#setTimeout() created a new WeakRef each time it replaced a timeout callback.
The parser instance is stable for the socket lifetime, so the same WeakRef can be reused instead of allocating a new one for every timeout replacement.

Changes

• Store a single parser WeakRef on Parser construction.
• Reuse that WeakRef for both fast timer and native timer timeout callbacks.

Features

N/A

Bug Fixes

Avoid repeated WeakRef allocations when replacing parser timeout callbacks.

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

Assisted-by: openai:gpt-5.5

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.13%. Comparing base (efae3da) to head (fd4b3da).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5125      +/-   ##
==========================================
- Coverage   93.14%   93.13%   -0.01%     
==========================================
  Files         110      110              
  Lines       35908    36105     +197     
==========================================
+ Hits        33446    33627     +181     
- Misses       2462     2478      +16     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[mcollina]

instead of a try/catch, use t.after

[trivikr]

Done in fd4b3da

[mcollina]

lgtm