fix: fetch threads for manual poll wakes

[brickfrog]

Routes review/merge-decision poll events through the existing unresolved-thread snapshot fetch even when automerge is disabled, while keeping PRMerged out of the fetch path.

Verification: moon test --target native && moon run src/bin/choir_lint --target native (pass; 2019 tests).

Verification

Generated by Choir from commands executed in the leaf workspace.

• moon test --target native
  • exit: 0
  • head: d5a3790
  • output tail:

Warning: Main package `choir/src/bin/choir` uses blackbox-only test inputs (`_test.mbt` files) in package directory "/mnt/data/Code/choir/.choir/worktrees/ptz1-server-side-thread-count-1781390368945-1405698-0/src/bin/choir". Main packages will stop generating blackbox tests in a future release. Move public behavior into a non-main package and keep the main package as an entrypoint.
4
Total tests: 2019, passed: 2019, failed: 0.

• moon run src/bin/choir_lint --target native
  • exit: 0
  • head: d5a3790

[brickfrog]

Choir: GitHub Actions rollup reports all checks successful on the latest head — re-check review/merge policy on GitHub (not an approval or merge signal by itself).

[brickfrog]

Choir: GitHub Actions rollup reports all checks successful on the latest head — re-check review/merge policy on GitHub (not an approval or merge signal by itself).