fix(cli): emit JSON for recording validation errors

[yashranaway]

with --json, a bad record flag like a zero or NaN duration, zero fps, or no target exited with code 1 and nothing on stdout. the check ran before either of the json error handlers, so scripts and agents parsing the output just got an empty response.

now validation and recording errors share one handler, which also removes the two copies that were wrapping foreground and detached runs. plain text output and exit codes are the same as before. the test runs every bad flag through record, record start and detached start.

🤖 Generated with Claude Code

Confidence Score: 5/5

The PR appears safe to merge.

Summary

Recording validation errors now produce JSON error events through the same handler as foreground and detached recording errors.

• Recording starts now report every failure as a JSON error event.

_{Reviews (1) · Last reviewed commit: "fix(cli): emit JSON for recording valida..." · Reviewed by Greptile}

[yashranaway]

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