docs(ui): name the stat-card selector the stylesheet actually defines

[argszero]

Summary

ui/README.md told readers the stat-card hover lift lives on .stat:hover, and the comment above .stat-card in ui/css/style.css said that class is "provided as an alias of .stat". Neither is true: the stylesheet defines zero .stat rules — git grep -nE '^\s*\.stat[ ,{:}]' -- ui/css/style.css returns nothing, class="stat" appears nowhere under ui/, and the only .stat text left in the sheet sits inside that comment (so a string search calls the name "present" while no rule declares it). The hover lift is on .stat-card:hover (ui/css/style.css:1110).

Both carriers of this one fact name a selector without a rule, and each one is what the next reader checks: the README line is the only statement of the convention, and the stylesheet comment is where the "alias" claim is learned.

The rename is not a judgement call: 75dcb2c (#154, shared component layer) deleted the .stat family and introduced .stat-card, and updated neither carrier — the README line was written by bbde077 (#52) when the class really was .stat, and the "alias" comment was written in the same commit that removed it. The design prototype uses .stat-card / .stat-card.accent / .stat-grid, and the direction is unambiguous: no .stat rule has existed since #154.

Related Issue

None — found while re-scanning ui/README.md for claims that do not match the code.

Changes

• ui/README.md: the stat-card hover line now names .stat-card:hover, with an inline correction note naming the component-layer change (75dcb2c / feat(ui): add shared component layer (stat-card/pill/tag/toolbar/bar-list) + define missing button variants (rant 2026-09-11, PR3) #154) that removed the .stat family
• ui/css/style.css: the comment above .stat-card states that the class replaced the historical .stat name, instead of claiming an alias that never existed
• ui/index.html: stylesheet cache-bust token bumped (?v=20260924-1 → ?v=20260924-2) — every previous change to ui/css/style.css did the same (8 of the last 8 commits touching that file also touched ui/index.html)
• No config or data-structure changes

Tests

• cargo test — 413 passed, 0 failed (identical to the base commit)
• cargo fmt --check — clean
• cargo clippy --all-targets -- -D warnings — clean
• No new unit tests: documentation- and comment-only change, no behaviour to assert
• Manually re-checked after the edit: still zero .stat selector rules, still zero class="stat" sites

Checklist

• Branch name follows the convention (docs/<description>)
• Commit message uses Conventional Commits (docs(ui): …)
• Single responsibility, minimal change (3 files, 4 insertions, 3 deletions)

[argszero]

Committer review (self-PR; GitHub will not let an author approve their own PR, so this is posted as a plain comment).

Claim checked against the tree, not the prose. On the base commit:

• git grep -nE '^\s*\.stat[ ,{:}]' -- ui/css/style.css → no match: the stylesheet declares no .stat rule.
• Every .stat hit in the sheet is .stat-grid / .stat-card or prose inside a comment (ui/css/style.css:1102).
• class="stat" → no site under ui/.
• The lift described by the README line is on .stat-card:hover (ui/css/style.css:1110), so the documented selector simply had no rule behind it.

Rename is traced, not inferred. 75dcb2c (#154) deletes .stat, .stat:hover, .stat .label, .stat .value, .stat .sub and adds the .stat-card family — in the same commit that writes the "provided as an alias of .stat" comment. The README line predates it (bbde077 / #52). Both carriers therefore name a selector that stopped existing in #154, and the correct name is the one the prototype uses (docs/prototype/…: .stat-card / .stat-card.accent / .stat-grid).

Scope. Documentation- and comment-only; no rule added, nothing renamed in code. Keeping the stylesheet comment in scope is deliberate — it is the second carrier of the same false fact, and a reader who checks the CSS would otherwise be told the alias exists.

Local verification on the branch tip (123d916). cargo test → 413 passed / 0 failed (same count as the base commit); cargo fmt --check clean; cargo clippy --all-targets -- -D warnings clean. Re-ran both tree checks after the edit: still zero .stat rules, still zero class="stat" sites. Cache-bust token bumped because ui/css/style.css changed, matching the 8/8 precedent of previous stylesheet commits. CI: msrv pass, test / fmt / clippy pass.

Merging.