t27f: deck look -- every reel scene is a presentation slide by default #9978

Problem

specs/t27f/reel.t27 (#9965, PR #9966) fixes the numbers of a T27F reel, but the frame is just the honeycomb filling the screen. The owner asked for the default look to be presentation slides, in the style of the Tome deck at tomeapp.ai/showcase/ccIzxAeYpq39I6HMWzwhe: each scene a slide.

What the Tome deck does (studied 2026-10-17, ten 2752x1536 slides)

• 16:9, near-black backdrop with soft aurora ribbons
• text on a glass card: faint white fill, thin light border, round corners
• big bold sans headlines, at most two lines, at most four short rows
• usual slide: card on the left, one glowing object on the right; the cover is one huge centred headline over a full-bleed picture

Plan

New spec specs/t27f/deck.t27 (module T27fDeck) that imports reel.t27 and decides, as numbers a host draws:

• the default look (DECK) and preset (16:9 wide)
• a layout per scene kind (cover, stage, split) with regions in permille, stacked for portrait frames
• the reel camera window fitted whole into the hero region, so focus+context holds on every slide
• type sizes per preset, a 2-line / 4-row rule, and text that does not fit becomes a second slide, never a smaller font
• card fades so text is never on screen while the camera moves
• a palette whose decoration stays away from the status colours (Tome's cyan ribbons would read as verified on our map), and a contrast floor for text on glass
• the hero is always the map itself, never a generated picture

Done when

Tests and invariants pass on the lab, 0 vacuous passes, each rule has a negative control that fails its own test.