REST + CLI mirror for loopover_check_improvement_potential

[JSONbored]

Context

The MCP tool loopover_check_improvement_potential (src/mcp/server.ts:2111, via checkImprovementPotential at src/mcp/server.ts:3638-3651) is a deterministic, rate-limited-only pure function over buildStructuralImprovementAssessment(input). Its sibling deterministic tools (loopover_check_slop_risk, loopover_check_issue_slop, loopover_lint_pr_text, loopover_validate_config) all already have POST /v1/lint/... REST routes and CLI mirrors. This one has neither.

Requirements

• Add POST /v1/lint/improvement-potential in src/api/routes.ts delegating to buildStructuralImprovementAssessment.
• Add an improvement-potential CLI subcommand mirroring slopRiskCli's shape.

Deliverables

• POST /v1/lint/improvement-potential route
• improvement-potential CLI subcommand
• Unit test

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

Structural improvement-potential checks are available over REST/CLI, matching the other deterministic lint tools' parity.

Links & Resources

Precedent: app.post("/v1/lint/slop-risk", ...) (src/api/routes.ts:3164) + slopRiskCli (loopover-mcp.js:3098-3124).

[linear-code]

JSO-4562

[RealDiligent]

Working on this — REST + stdio mirror for loopover_check_improvement_potential, matching the /v1/lint/* parity pattern.