t27f: idea factory batch -- five ideas cover all five presets under PRESET_AUTO, and the compiled binary agrees with the spec #10815

Part of epic #10560. Follows #10803 (PR #10806).

Boundary

specs/t27f/idea_factory.t27 (tests only), .trinity/seals/t27f_idea_factory.json, .claude/skills/t27f/SKILL.md. No change to main, the presets, or particle_ds.

Scenarios

• PR t27f: idea factory picks its style preset from a hash of the idea, PRESET_AUTO (Closes #10803) #10806 adds PRESET_AUTO, which picks a preset from FNV-1a 32 of the idea. It was checked only in the t27c interpreter. No compiled binary has ever rendered with PRESET = PRESET_AUTO, so nothing shows that the generated code picks the same preset as the spec.
• Competitors handle batches as a first-class feature. Canva Bulk Create turns one data table into many designs, and Remotion renders many videos from inputProps. The factory has no tested batch, and no preview of one.

Requirements

• FR-001: The spec MUST pin a batch of five ideas whose AUTO presets cover all five presets (noir, neon, trit, paper, rain).
• FR-002: For each idea in the batch, the frame stream of the generated binary built with PRESET_AUTO MUST be byte-identical (md5) to the stream built with the pinned preset given explicitly.
• FR-003: A negative control MUST show that the same idea with a different preset gives a different stream.
• FR-004: The t27f skill MUST record the batch recipe and the cross-backend check.

Criteria

• t27c test-report passes, 0 vacuous, on the Railway lab, and a mutant of the pinned preset is killed.
• Lab log: 5 of 5 SAME, NEG DIFF.
• A 720p batch preview and a tile sheet sit in the session notes folder (not committed).
• Seal re-saved, --verify MATCH.

Success Criteria

• t27c test-report --spec specs/t27f/idea_factory.t27 passes with 0 vacuous tests on the Railway lab and kills a mutant of the pinned preset → exit 0
• Lab log shows 5 of 5 SAME, NEG DIFF for the five ideas comparing PRESET_AUTO binary output vs explicit preset binary output → exit 0
• Seal file .trinity/seals/t27f_idea_factory.json re-saved and t27c seal verify .trinity/seals/t27f_idea_factory.json reports MATCH → exit 0
• Skill file .claude/skills/t27f/SKILL.md records the batch recipe and cross-backend check → exit 0