CLI mirror for loopover_monitor_open_prs

[JSONbored]

Context

The MCP tool loopover_monitor_open_prs (src/mcp/server.ts:2012, implemented by monitorOpenPullRequests at src/mcp/server.ts:3542) and the REST route GET /v1/contributors/:login/open-pr-monitor (src/api/routes.ts:3117, gated by requireContributorAccess) both already do this work. No loopover_monitor_open_prs entry exists among the registerStdioTool(...) calls in packages/loopover-mcp/bin/loopover-mcp.js (confirmed via full extraction, cross-checked against the pinned tool count in test/unit/mcp-tool-rename-aliases.test.ts).

Requirements

• Add registerStdioTool("loopover_monitor_open_prs", ...) in loopover-mcp.js proxying GET /v1/contributors/{login}/open-pr-monitor.
• Resolve login from --login/LOOPOVER_LOGIN/active session the same way decisionPackCli does.
• Support --json output.
• Update the tool-count assertion in test/unit/mcp-tool-rename-aliases.test.ts (63 → 64).

Deliverables

• registerStdioTool("loopover_monitor_open_prs", ...) in loopover-mcp.js
• Login resolution matching decisionPackCli's pattern
• Updated tool-count assertion
• Unit test in the mcp-cli-tools.test.ts style

Test Coverage Requirements

99%+ Codecov patch coverage on every changed line and branch in the new route/tool/CLI code, plus a test asserting output parity between the mirrored surfaces for identical input.

Expected Outcome

A contributor can run loopover-mcp from the CLI to monitor their own open PRs, without needing the MCP server surface.

Links & Resources

Precedent: registerStdioTool("loopover_get_pr_reviewability", ...) at loopover-mcp.js:1192 — identical thin apiGet proxy shape.

[linear-code]

JSO-4546