fix(#915): derive theme lists, and classify scripthammer-forge as dark

[TortoiseWolfe]

Closes #915

The defect

Six test files each typed a theme list by hand against src/config/themes.ts, and every one missed scripthammer-forge — the third house theme, which shipped after they were written.

The sharpest instance is color-contrast.spec.ts, the AAA gate. #411 built it after a hand-written four-route list let a 6.44:1 eyebrow reach main behind 17 green checks. It enumerates its routes for exactly that reason — and hand-wrote its themes. Its comment read "Both custom themes covered", and "Both" was the completeness claim, stale the day forge landed. Same defect, same file, other axis.

Measured:

color-contrast.spec.ts   1,223 -> 1,834 cases
forge cases                  0 ->   611

A real bug fell out, and it is user-visible

scripthammer-forge ships base-100: #0f0d0b — near black — and was absent from DARK_THEMES in src/utils/theme-utils.ts, whose own docblock says it drives "map tiles, Disqus, Calendly, Cal.com, and Leaflet CSS."

On forge, every one of those rendered in light mode over a near-black page.

It surfaced only because embed-theme-contrast.spec.ts mirrored that list by hand and the new guard flagged the copy. The mirror had not drifted — 13 against 13. Both were wrong together, which is exactly why comparing a mirror to its source could never have revealed it.

What changed

src/config/themes.ts	exports HOUSE_THEMES; HOUSE_THEME_COUNT derives from it
5 specs	import instead of restating
src/utils/theme-utils.ts	forge added to DARK_THEMES

The count in themes.ts was already correct. The prose beside it said "34 total, of which 2 are ours" — written for two house themes, in the one module whose stated job is stopping numbers from drifting.

depth-tokens.spec.ts had both patterns in one file: two hand-typed at :286 while :367 derived all three correctly. theme-switching.spec.ts already imported THEME_COUNT to assert the count, then listed 32 of 35 members beside it.

Two guards, and the second is the one that matters

The first forbids a hand-typed house theme in any of the five. It strips comments first, because several of those files now discuss the theme names while explaining why they derive them — matching that prose would fail a correct file.

The second computes each house theme's base-100 luminance and requires DARK_THEMES to agree. Asserting "forge is in DARK_THEMES" would pass the moment someone typed it in, and would say nothing about the fourth house theme.

mutation	result
remove forge from DARK_THEMES (the actual bug)	red — "luminance 0.006, DARK, is NOT in DARK_THEMES"
hand-type a house theme back into the AAA gate	red
un-derive HOUSE_THEME_COUNT	red

Deliberately not done

tests/e2e/pages/ThemePage.ts also holds a hand-typed list of 31, and the audit counted it as a sixth instance. The file is entirely unused — nothing outside ThemePage.ts references ThemePage. Its list is dead code, not a coverage gap, and deleting an unused page object belongs with #547's decision about unused components.

A note on risk

This adds 611 whole-page axe cases on a theme that has never been swept. I checked the token-level verdict first — src/config/theme-contrast.json rates forge AAA, textRatio 13.37, uiRatio 7.05 — so a red gate is unlikely. If one appears, it is a real accessibility finding on a shipped theme, which is the entire point of closing the hole.

Verification

type-check / lint     clean
test:scripts          539 passed
theme unit tests      79 passed (7 files)

🤖 Generated with Claude Code