feat(langchain): Record reasoning token usage attribute

[alexander-alderman-webb]

Description

Record the reasoning token count from the provider-agnostic UsageMetadata dictionary.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Codecov Results 📊

✅ 99560 passed | ⏭️ 6671 skipped | Total: 106231 | Pass Rate: 93.72% | Execution Time: 343m 7s

📊 Comparison with Base Branch

Metric	Change
Total Tests	—
Passed Tests	—
Failed Tests	—
Skipped Tests	—

✨ No test changes detected

All tests are passing successfully.

✅ Patch coverage is 94.44%. Project has 2507 uncovered lines.
✅ Project coverage is 90%. Comparing base (base) to head (head).

Files with missing lines (1)

File	Patch %	Lines
sentry_sdk/integrations/langchain.py	93.75%	⚠️ 1 Missing and 2 partials

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.99%    90.00%    +0.01%
==========================================
  Files          193       193         —
  Lines        25061     25073       +12
  Branches      9058      9066        +8
==========================================
+ Hits         22552     22566       +14
- Misses        2509      2507        -2
- Partials      1439      1438        -1

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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