CLI test coverage: resolveGifOption, resolveRecorder, and flag→resolver wiring

[jbrecht]

From the qa-engineer's PR #64 audit. Severity: LOW (test debt). #64 added a vitest harness to packages/cli and wired pnpm -r test into CI, so these are now cheaply testable — they weren't before.

Gaps

• resolveGifOption (packages/cli/src/render.ts) — flag/config merge + --gif-steps implies --gif: untested.
• resolveRecorder — valid/invalid value handling (throws on bad input): untested.
• Flag→resolver wiring (P2 from the audit) — nothing asserts the Commander option name actually reaches the resolver. A camelCase typo (renderConcurrency vs render-concurrency) would silently fall back to serial with no test catching it. Either a thin argv-parse test through the Commander program, or accept it stays manual.

Acceptance

• resolveGifOption and resolveRecorder have unit tests in packages/cli/test/.
• Decide on (and ideally add) a Commander-wiring assertion for the render flags.