REST + CLI mirror for loopover_watch_issues

[JSONbored]

Context

The MCP tool loopover_watch_issues (src/mcp/server.ts:2199, via watchIssues at src/mcp/server.ts:3849-3869) manages watch/unwatch/list issue-watch subscriptions, self-scoped via requireContributorAccess + requireWatchableRepo. No REST route exists for this, and no CLI mirror exists.

Requirements

• Add GET/POST/DELETE /v1/contributors/:login/watches in src/api/routes.ts reusing the same repository functions and requireContributorAccess/canWatchRepo gates.
• Add a CLI mirror (e.g. loopover-mcp watch <owner/repo> [--labels a,b] / unwatch / list).

Deliverables

• GET/POST/DELETE /v1/contributors/:login/watches routes
• CLI watch/unwatch/list commands
• Unit tests

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

Issue-watch subscriptions are manageable over REST/CLI, not just MCP.

Links & Resources

Precedent: the contributor-scoped route family cited above, plus requireWatchableRepo at src/mcp/server.ts:2966-2970 for the access check to reuse verbatim.

[linear-code]

JSO-4560