[kayahk]

Summary

Implement the optional Git provider list_issues operation: list repository issues with state and cursor, exclude pull requests from the response, and preserve the continuation cursor even when a page contains only pull requests. The existing get_issue provider operation is reused.

Part of #32.

Dependencies — draft, not merge-ready

• SDK contract: feat(gitprovider): add optional issue listing plugin-sdk-go#15
• Core API and MCP tool: feat(git): add repository issue listing tool paca#689
• backend/go.mod temporarily replaces the SDK with the exact companion fork commit so CI can exercise the complete change. Replace it with a released upstream SDK version before merging; do not merge the fork dependency.
• WASM transport overflow: Handle oversized WASM host responses without misleading fetch errors plugin-sdk-go#16. One issue per page mitigates common large pages but does not fix the underlying arena limit; a single oversized response can still fail. A pull-request-only page can be empty while still supplying next_cursor; clients must continue until the cursor is absent.

Validation

• go test -race ./... and go vet ./... in backend using the pinned SDK fork.
• Tests exercise provider wire dispatch, default and invalid inputs, error propagation, pull-request filtering and cursor handling; conformance runs against the fake GitHub.

No live deployment or TinyGo build has been verified locally.

[pikann]

LGTM! Thanks for your contribution.
I'll merge this PR and continue working on Paca-AI/plugin-sdk-go#16.