fix(styles): tokenise editor chrome colours and guard component styles

[betterthanclay]

What

The slash palette painted linear-gradient(rgba(15, 23, 42, 0.98), rgba(15, 23, 42, 0.94)) over
var(--nightfire-color-surface) and let the shipped light theme's dark text sit on top. Measured
from the composited layers in the triage note, the search input was 1.00:1 and the command labels
1.23:1 — illegible in the theme this package ships, in a published release.

This makes the palette light chrome, as contract 003 already described the editor layer, and adds
the guard that stops the next literal.

• Literals removed (8, two files). SlashCommandPalette.svelte: the gradient, its
  box-shadow rgba(15, 23, 42, 0.28), the input background rgba(15, 23, 42, 0.82), and the
  selection pair rgba(96, 165, 250, 0.32) / rgba(59, 130, 246, 0.14).
  editor/NightfireMultiBlockItem.svelte: #f87171, rgba(239, 68, 68, 0.15),
  rgba(239, 68, 68, 0.4).
• One token added. --nightfire-color-selection: #3b82f6 in ts/src/styles.css, used for the
  selected item's border and background at the alphas the component already used
  (color-mix(... 32%, transparent) and ... 14% ...). The danger state reuses the existing
  --nightfire-color-danger the same way. The palette root sets
  color: var(--nightfire-color-text) explicitly, so the items' color: inherit cannot take the
  host page's text colour.
• The check. ts/scripts/check-style-literals.ts fails on a colour literal (hex, functional
  notation with literal arguments, CSS named colours) in any ts/src/**/*.svelte style block.
  Exceptions: transparent, currentColor, inherit. Wired into health as
  check:style-literals, so every lane runs it. ts/tests/nightfire/style-literals.test.ts holds
  the guard biting and the shipped tree passing.
• Two counts. docs/architecture/core-package-vocabulary.md and
  docs/contracts/003-styling-and-restyling.md read 25, and the test fails if either disagrees
  with styles.css. PROVENANCE.md records the token as locally authored beside
  --nightfire-color-focus. Radii, spacing and font literals remain unguarded; the triage note
  keeps that gap open.

Interaction oracle

Invariant	Proof
The palette is legible in the shipped default	its style block references the text and surface tokens and holds no colour literal; the root sets the text colour
No component style carries a colour literal	planted #ff0000, rgb(15 23 42) and rebeccapurple are all reported, exit 1; the shipped head passes
One declared value per token	25 declarations, all consumed, and both documents read 25
The danger state keeps its meaning	the multi-block item references --nightfire-color-danger
Renderers are untouched	no renderer references a token or a scoped style
Nothing else regressed	the component suite and its a11y assertions pass untouched

jsdom does not composite backgrounds, so the component suite cannot assert rendered contrast; the
token-reference assertion plus the no-literal check is the honest floor here. Computed from the
declared values: --nightfire-color-text on --nightfire-color-surface 17.74:1, the muted token on
it 4.83:1, and --nightfire-color-text on the selected item's 14% tint 15.17:1. The danger icon's
hover tint gives --nightfire-color-danger 3.10:1, above the 3:1 WCAG non-text floor.

effigy qa

effigy qa passed (exit 0) at beb9ccaa5387974945c0c03bc8875afeb76f8cf0:

• export proof passed: 23 explicit subpaths resolve
• boundary proof passed: forbidden graph absent; core 3995 bytes; validation 3977 bytes; renderer 5716 bytes/4 inputs and editor-free
• schema proof passed: 11 documents, 7 core payloads, 4 positive cases, 3 negative cases
• style literal proof passed: no colour literal in any ts/src/**/*.svelte style block
• version sync passed: npm and Cargo 0.2.0; both languages and Cargo packaging consume root wire v1
• pack proof passed: 87 files, 56125 bytes
• Cargo package proof passed: unpacked nightfire 0.2.0 tests consume the root fixture
• npm Git-consumer proof passed at beb9ccaa5387974945c0c03bc8875afeb76f8cf0
• cargo Git-consumer proof passed at beb9ccaa5387974945c0c03bc8875afeb76f8cf0
• docs paths/links/index/forbidden/contains/heading checks passed; release-automation verified
• svelte-check: 0 errors, 3 pre-existing warnings in ts/src/video/VideoEditor.svelte

Unit, component, sanitization and Rust suites passed. The palette's existing component suite is
untouched.

Out of scope

No renderer, schema, payload, export map, version or consumer change. No merge, tag or publish.

[betterthanclay]

Approved for merge at exact head beb9cca.

Findings: none.

Review scope:

• Confirmed the diff is limited to the editor color-literal repair, the selection token, the component-style guard and tests, token-count/provenance/changelog updates, and related canonical documentation.
• Confirmed no renderer, schema, payload, export, Rust, version, release, or consumer changes.
• Confirmed SlashCommandPalette now uses the shipped surface, field, border, selection, and text tokens; its root explicitly sets the text color.
• Confirmed NightfireMultiBlockItem reuses the existing danger token for its danger state.
• Confirmed the guard scans all ts/src/**/*.svelte style blocks and the tests cover planted hex, functional, and named-color literals, token references, keyword exceptions, shipped-tree coverage, renderer isolation, token counts, and text/surface contrast.
• The repository's review-oracle contract defines this package's in-repo interaction/token checks as the acceptance surface; the absent demo surface is therefore not a review blocker.

Validation:

• effigy check:style-literals passed.
• effigy test:components passed, including slash-palette filtering, keyboard navigation, empty state, and Escape behavior.
• effigy test:unit passed.
• effigy test:sanitization passed.
• effigy health passed.
• effigy qa passed, including all configured tests, package proofs, both Git consumers, and docs QA.
• GitHub Release gate passed.
• Worktree was clean before and after review; HEAD remained beb9cca.

The three svelte-check warnings in VideoEditor.svelte are pre-existing and unrelated to this PR. Radii, spacing, and font literals remain explicitly outside this lane's guard and are not merge blockers here.