fix(wizard-ci): make snapshot runs render colour and report real failures

[gewenyu99]

Four fixes to the snapshot harness, all found while running wizard-ci against the wizard 2.71.0 RC.

snapshots.ts HTML-escaped the raw .ans frames into a <pre>, so every rendered PNG showed literal escape codes instead of the terminal — it now parses the SGR grammar rowToAnsi emits. snapshots-review.ts cast away the commitAndCreatePR result and never checked success, so a commit that never landed printed ✓ review PR: (created) and exited 0; checking it is what surfaced the third bug, createSignedCommit creating the branch ref before the commit and dying on Reference already exists for every retry. Finally e2e.ts asserted non-integration programs end on a screen literally named outro, scoring a fully successful upload-source-maps run as a failure because its outro is source-maps-outro. --render-only re-renders from frames already on disk, so a renderer change no longer costs a 20-minute agent run.

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