chore(mcp): Replace deprecated mcp.prompt.name with gen_ai.prompt.name

[alexander-alderman-webb]

Description

See the deprecation in sentry-conventions:

https://github.com/getsentry/sentry-conventions/blob/7abb07791bc03f3a5aa50eab818b1782a4ddcb16/model/attributes/gen_ai/gen_ai__prompt__name.json

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 📊

✅ 56869 passed | ⏭️ 2727 skipped | Total: 59596 | Pass Rate: 95.42% | Execution Time: 150m 52s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -80755
Passed Tests	📉 -76260
Failed Tests	—
Skipped Tests	📉 -4495

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2081 uncovered lines.
❌ Project coverage is 89.99%. Comparing base (8b242f5) to head (c51c350).

Coverage diff

@@            Coverage Diff             @@
##        master       #PR       +/-##
==========================================
- Coverage    90.35%    89.99%    -0.36%
==========================================
  Files          202       185       -17
  Lines        26551     20785     -5766
  Branches      9856      7188     -2668
==========================================
+ Hits         23988     18704     -5284
- Misses        2563      2081      -482
- Partials      1487      1205      -282

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