Fail closed when a named profile file is missing

[TheGreatAxios]

Summary

• An explicit --profile name (or a project profile key) whose file does not exist now throws, naming the missing path, instead of silently running on defaults
• Optional absence of the project overlay profile.json stays silent

Verification

• bun test src/profiles.test.ts — 14 pass, exit 0
• Independent critic: ready, no blocking findings

Fixes CL-7636

[linear-code]

CL-7636

[TheGreatAxios]

Review · Comment

Missing named profile files fail closed in resolveProfile; a missing project overlay stays optional.

Findings

• src/profiles.test.ts — merge test still reimplements { ...namedProfile } and comments that home cannot be injected, while this diff adds home and uses it in the new tests. Drive that merge through resolveProfile(cwd, undefined, home).

[TheGreatAxios]

Critic · Comment

Throw after loadProfile null is the right layer. ENOENT-only null keeps JSON/schema errors distinct. Optional third home arg; loadConfig still calls the two-arg form.

Findings

• Merge test comment is now false; project-over-named merge is not actually executed via resolveProfile.