feat(ui): migrate ToolActivity card shell onto @maka/ui chat primitives (#332 PR3b)

[Astro-Han]

Summary

Moves the ToolActivity card shell — the inline section + count pill, the <details> card, its <summary> header row + status dot, the body / intent, and the args <pre> override — onto the @maka/ui chat substrate, retiring the bespoke .maka-tool* / .toolInline / .toolItem / .toolArgs CSS with zero visual change. This is PR3b of the #332 conversation-flow governance pass, following PR1 (#334, bubble/row shell), PR2 (#337, turn markers), and PR3a (#348, tool live-output stream).

The static shell literalizes onto a new internal toolVariants cva exactly as PR2/PR3a did. Three pieces escape the leaf-literal proof and stay a small named residue re-keyed off the retired .maka-tool class onto the governed [data-slot="tool"] hook: the card mount entrance (transition + @starting-style, which only paints on the first frame), the native <summary> marker reset (pseudo-elements), and the running dot's @keyframes maka-tool-pulse ring (a keyframe is a global rule, not an element property). These are pinned by a cascade contract + the diff harness instead.

Why

Closes part of #332 (PR3b). The conversation-flow display is being migrated onto one @maka/ui substrate + a test net, one island at a time, with zero visual change. The tool card was the one remaining bespoke island between already-governed neighbours (bubble / marker / stream); lifting it now keeps the chat surface coherent and location-independent (status is a data-* vocabulary, not a descendant-selector coupling). The native <details> card and the .maka-turn-thinking block can later converge onto one Base UI Disclosure primitive — PR3b deliberately leaves both in the same shape (native details + named residue) so that structural pass is a clean follow-up, not a prerequisite.

Scope

Changed (three atomic commits):

• feat(ui): add internal toolVariants chat primitive — packages/ui/src/primitives/chat.tsx (the cva table; every value a LITERAL arbitrary utility compiling 1:1 to the retired declaration), packages/ui/src/index.ts (kept OFF the barrel like markerVariants / streamVariants — single consumer, relative import).
• refactor(ui): migrate ToolActivity onto toolVariants and retire .maka-tool* CSS — packages/ui/src/components.tsx (rewire + data-slot="tool"), apps/desktop/src/renderer/maka-tokens.css + styles/tool-output.css (delete the migrated rules; keep the [data-slot="tool"] entrance/marker residue + the @keyframes maka-tool-pulse ring). Consumer + CSS removal land together so the renderer orphan-selector contract stays green.
• test(ui): lock the migration with cascade contract + diff harness — see Verification.

Not included:

• ToolErrorBanner + .maka-tool-error* — already on the @maka/ui Alert primitive; its dead grid/icon/body/title classes and live copy-feedback tints are coupled to visible-copy-hygiene-contract, a different review lens. Separate PR (PR3c).
• The result-preview renderers (.maka-tool-diff* / .maka-tool-terminal* / .maka-office-document* / .maka-explore-agent* / .maka-load-tool-* / .maka-overlay-*) — separate components rendered inside the tool body, a different concern.
• The shared .maka-code inline-code base (Markdown / artifact previews use it too) — untouched; the args <pre> keeps the class and only its .toolArgs override moves.
• Base UI Disclosure unification of the card + .maka-turn-thinking — a later structural pass.

Verification

This repo has no CI; everything below was run locally.

• npm run -w @maka/ui test — 13/13 (adds a toolVariants literal/scale-drift + single-backslash waiting_permission runtime guard).
• npm run -w @maka/desktop test — 1613/1613 (adds chat-tool-card-cascade-contract.test.ts: retired selectors absent without touching .maka-tool-error* / .maka-tool-diff* / .maka-tool-terminal* / .maka-code; @keyframes maka-tool-pulse ring frames pinned; the [data-slot="tool"] entrance + marker residue pinned; the [open]>summary divider + running-dot literals + String.raw escape pinned; and a guard deriving the status set from STATUS_LABEL so every production status keeps a diffed row).
• npm run typecheck — clean across all workspaces.
• npm run check:chat-visual -- <pre-PR2 baseline.css> <head.css> (the computed-style diff, extended with a tool-card tree): against a pre-PR2 renderer CSS baseline (e033a8c4~1, which still carries the bespoke marker + stream + tool CSS), TOTAL DIFFS: 0 across 61 element/state rows + 2 ::before middots — including all 25 tool-card rows (every one of the six production statuses renders a card — pending included, proving the base border + gray-dot fallback it has no data-[status] branch for). Each card is rendered at its real isOpenByDefault state (pending/waiting/running/errored open, completed/interrupted collapsed), so the most common historical card — a settled, collapsed completed tool — is covered too: the collapsed summary's divider reads 0px vs the open card's 1px (the non-vacuous proof the collapsed branch is exercised), identical across main/head. Non-vacuous: the baseline and head bundles differ in source, yet the migrated chrome reads byte-identical computed style on both sides.
• The running dot is the one part the diff can't cover (animated → phase-dependent getComputedStyle); pinned by the @keyframes maka-tool-pulse frame contract + the chat.tsx literal.

User-facing impact

None — zero visual change by design, locked by the contract + diff above.

Reviewer notes

• The diff harness earned its keep: it caught a real literalization bug a source-only test would have missed. waiting_permission carries a literal underscore, and Tailwind turns a bare _ in an arbitrary value into a SPACE — so data-[status=waiting_permission] compiled to [data-status="waiting permission"] and the card/dot tint silently fell back to the base color (3 diff rows). Fixed with a String.raw \_ escape so the scanned source text and cva's runtime class agree on a single backslash; both contract tests now lock it (the four underscore-free statuses never had the problem).
• toolVariants is deliberately off the barrel (like markerVariants / streamVariants): one consumer, applied by relative import, so it stays an internal, freely-removable styling detail rather than public API.
• The status dot stays a toolVariants part, not a shared primitive like LiveIndicator: it is tool-specific (six states, a box-shadow ring pulse distinct from the maka-pulse opacity/scale breath), so there is no second consumer to justify promotion.
• The tests intentionally do NOT re-assert the static shell's per-part literals: that shell is proven by the computed-style diff, so re-stating the strings would only mirror the implementation. Source-string assertions are kept only for the escapes the diff cannot observe.
• Reduced-motion / visual-smoke suppression both ride GLOBAL * rules (maka-tokens.css / base.css), so — unlike LiveIndicator, a reusable primitive carrying its own motion-reduce: guards — the dot and card need no per-element motion utilities; the same global rules cover them as before.