feat(core): Full reworked, Prompt on the theme's ground, the switch knob (#154)

[Maxaubert]

Closes #154. Follow-up to #143 (PR #147), from the mockup and plan the owner approved on 2026-10-10 (research/prism-terminal/mockups/2026-10-10-full-style/). Spec: docs/superpowers/specs/2026-10-10-full-style-rework-design.md.

What changes

Full (choice 1A, choice 2 as the owner changed it)

• Finished: the icon's rainbow, solid, flowing slowly across the whole tab (p-mark-flow-fill, 228 px tile, 14 s). The dark badge and its foot line are gone. Its name ink is judged on the rainbow's worst colour (rainbowInk): black on Volt, the text on Paper.
• Working: the fill carries Minimal's own working mark on top. On Classic the run is the name's ink, so it is black on Volt's yellow-green (owner: "should be black and not like a faded arc yellow"). On Prompt the growing arrow edge sits in the ground-coloured gap, where black would disappear on a dark theme, so it keeps the shade that clears 3:1 on the fill and the ground (shadeOn: Volt #798f15, Paper #1c3e59). The spec records this split. The ride is gone.

Prompt on the theme's ground (choice 3A)

• An idle segment paints nothing, and the tab in front is --p-tab-active, the same as Classic. --p-seg and --p-seg-on are removed, along with their :root fallbacks and tests.
• The edge band tucks 1 px only under a segment that paints. A tuck under a see-through segment would widen the edge to 4.5 px.

Settings switches

• The ON knob is the new --p-switch-knob: black on a dark theme and white on a light one (measured from the ground). It flips to the other colour only where the default reads under 2:1 on the ON track (owner: "keep that to being black on dark themes and white on light themes ... only when the color is very close"). The rule is in core/renderer/lib/switchKnob.ts and is computed in chromeTokens. The track is unchanged.
• An opaque accent is held to 3:1 on the ground, which also keeps it clear of the default knob. So the flip only shows with a see-through accent: a pale one on Paper gives a black knob, a deep one on PT Default gives a white knob. The e2e measures both.

Core / Prism

This changes core/ (0.28.1 -> 0.30.0, above #153's 0.29.0), so merging ships it to Prism too. Prism is unaffected: its strip does not use resolveTabMark, markPalette or marks.css, and SWITCH_KNOB_ON is var(--p-switch-knob, var(--p-on-accent)). Prism keeps its current knob until it defines the token. App 0.35.1 -> 0.36.0.

Gates

• typecheck, lint (0 errors), unit 1611/1611
• e2e, one at a time: indicatorStyles, tabStyle, indicator, attention, accent, themeSwitch
• Screenshots in .e2e-shots/marks-* (Volt and Paper, Classic and Prompt), checked against the mockup's overview.png.

🤖 Generated with Claude Code

https://claude.ai/code/session_01FHHaWKR4M5QtW7Wecyuk4t