feat: handle bandwidth test requests from server

- Update to actions-proto-go v0.5.7 with RequestBandwidthTest field
- Add SetBandwidthManager method to Poller
- Check FetchTaskResponse for bandwidth test request
- Include bandwidth in capabilities sent to server

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

go.sum

@@ -6,8 +6,8 @@ cyphar.com/go-pathrs v0.2.1 h1:9nx1vOgwVvX1mNBWDu93+vaceedpbsDqo+XuBGL40b8=
 cyphar.com/go-pathrs v0.2.1/go.mod h1:y8f1EMG7r+hCuFf/rXsKqMJrJAUoADZGNh5/vZPKcGc=
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 dario.cat/mergo v1.0.0/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
-git.marketally.com/gitcaddy/actions-proto-go v0.5.6 h1:G7T0vpx8HyCFWd0YMJ9sp8rCsWtzFrCJK4BMdOFJa1A=
-git.marketally.com/gitcaddy/actions-proto-go v0.5.6/go.mod h1:RPu21UoRD3zSAujoZR6LJwuVNa2uFRBveadslczCRfQ=
+git.marketally.com/gitcaddy/actions-proto-go v0.5.7 h1:RUbafr3Vkw2l4WfSwa+oF+Ihakbm05W0FlAmXuQrDJc=
+git.marketally.com/gitcaddy/actions-proto-go v0.5.7/go.mod h1:RPu21UoRD3zSAujoZR6LJwuVNa2uFRBveadslczCRfQ=
 gitea.com/gitea/act v0.261.7-0.20251202193638-5417d3ac6742 h1:ulcquQluJbmNASkh6ina70LvcHEa9eWYfQ+DeAZ0VEE=
 gitea.com/gitea/act v0.261.7-0.20251202193638-5417d3ac6742/go.mod h1:Pg5C9kQY1CEA3QjthjhlrqOC/QOT5NyWNjOjRHw23Ok=
 github.com/AdaLogics/go-fuzz-headers v0.0.0-20230811130428-ced1acdcaa24 h1:bvDV9vkmnHYOMsOr4WLk+Vo07yKIzd94sVoIqshQ4bU=