feat(ui): Visual System 2.0 — T5 detail polish (six chapters)

[jackwener]

Summary

Task #173 — the six-chapter detail-refinement program over the 2.0 foundation, 17 commits, each individually gated (typecheck / ui build / lint / format / dead-css).

• A · State feedback: DESIGN.md §10 ratified (three empty-state tiers with an anti-inflation lock, loading protocol keyed on structural predictability, the search/filter clear-action rule with its rationale). All 39 EmptyState sites conformed (24 fixed — including a filter dead-end with a disabled exit, and five WeChat dialog states untangled into Spinner/Banner/tier-3); memory page's hand-rolled empties migrated; MCP loading text → row-shaped skeletons; onboarding's static first-paint bars → pulsing Skeletons; dead data-pending attributes → native isLoading.
• B · Interaction completeness: the never-defined --ease-standard retired from all five references (product scale or by-value lockstep); seven keyboard-focus gaps closed; one global prefers-reduced-motion rule for real users; hover washes converged to a two-lane rule (§9).
• C · Icons & alignment: the five-rung ICON_SIZE scale (meta 13 / control 14 / chrome 16 / empty 20 / plate 28) across 226 glyph sites — 96% of sized sites move ≤1px; 56 unsized sites (24px defaults and the squashed-in-slot class) fixed; plate ladder named with a 58–64% fill convention; one right-edge cap for settings row ends.
• D · Type & spacing: the orphan section-header system deleted; permission center rejoins the sm tier; heading-as-row-label fixed; title→subtitle pairs at one 2px gap; off-ladder tracking zeroed; the 11px composer tooltip ratified as a documented Astryx-lockstep exception.
• E · Dialect cleanup: the import dialog fully translated from vendor tokens onto the product contract; the paired QR dialogs share one --qr-frame-size and width.
• F · High-perception steals: one app-wide scrollbar recipe (both reference systems' convergent solution); quiet tabular tab counters — with the references' mono component rejected by the Role-Not-Axes rule, reasoning in-source.

Verification

• Geometry round (second agent, same-methodology census with settle wait): six fixtures button/svg counts identical to main; zero control escape; overflow probes clean. Two interim census alarms were falsified as probe timing bias (no settle wait bites the slower-rendering side) — methodology now recorded.
• Focus-ring clipping probe found three real classes → fixed via inset rings (breadcrumb, titlebar strip, turn-footer actions); scroll-to-bottom's identical clip is vendor-internal (upstream item, with popper/bubble themeProps asks).
• Known follow-ups (not in this PR): skills-page loading signal through the app-shell hook; 4px chat-subtree horizontal overflow (present on main, T6 candidate); three transient-state screenshot verifications (conditional surfaces, supplementary).

Merged under the owner's no-CI-wait directive; CI runs post-merge, fix-forward.