fix(cache): honor configured response cache paths

[christso]

Bead: av-vwa.3

Summary:

• Honor TS config response cache paths and add CLI cache path affordance.
• Keep YAML cache_path as the wire key and document response cache vs replay.
• Add focused cache/config/programmatic coverage and CLI integration coverage.

Verification from worker handoff:

• bun --filter @agentv/core build
• bun --filter agentv build
• bun --filter @agentv/core typecheck
• bun --filter agentv typecheck
• focused cache/config/programmatic/loader tests
• bun test apps/cli/test/eval.integration.test.ts
• bun run test
• bun run validate:examples

Integration review: branch is 0 behind / 1 ahead of current origin/main.