feat(ui-web): draw each settings section's own shape while it waits

[arelchan]

Summary

Every settings section waited behind the same dashed box with "Loading" in it.
That box is a line of display text and 34px of padding, so the panel was a 90px
strip that became whatever the section is the moment the snapshot landed, and a
section is rarely one line: the usage page is four cards and a chart, the
provider catalogue is a full-height two-column grid.

The waits the pages own drew even less. The usage totals and the archive list
each replaced a card's worth of rows with a single grey word inside it, and the
card shrank to fit the word. Channels, schedules and the schedules' run history
drew nothing at all, and an empty column beside an empty pane is what "there are
no channels" looks like.

So a section draws its own anatomy instead, in the section's own card, row and
list classes: the skeleton is the page with its words replaced by bars, which is
what makes the swap a fill-in rather than a resize. Twelve places in all:

• the settings panel, with a shape per section (general, usage, providers,
  models, skills, tools, plugins, archive, about);
• the onboarding wizard's two step bodies, which wait on the same snapshot;
• the five a page or a drawer fetches for itself: usage totals, archive list,
  skill body, plugin credential fields, vendor model list;
• the four lists the two-pane frame holds (channels, schedules, memory) and the
  schedules' run history.

Key decisions:

• The usage range picker stays live through the page's own wait: the range is
  the reader's state, not the counter's, so only what the counter answers is
  drawn as bars.
• The vendor list keeps the line naming the vendor being asked, with the rows
  under it: a shape cannot say which vendor.
• The bar is the one shape added, and it is added three times. A class belongs
  to one namespace (scripts/check-class-namespace.mjs) and the existing
  skel/sk pair is pinned at the two domains that already name it, so the
  settings sheet, the two-pane frame and the cron sheet each carry their own.
  All three are a translucent wash rather than a named surface, because these
  sit on the card, on the catalogue's rail and inside the model popover and no
  one named colour reads against all three.
• Channels and schedules draw the wait in the unentered state too: the
  condition is the same !loaded && !rows.length either way, the box is hidden
  until the section opens, and opening it starts the load. This is what grows
  both boot goldens by the channels list's wait.

Also here:

• _resetForTests clears the settings store's in-flight load. A case that
  mounted the dialog on a load it never resolved left refresh handing the same
  promise to every later caller, so one failed assertion turned the four cases
  after it into timeouts.
• The run history says the schedules' own word (gui.cron.reading) rather than
  the hub's. gui.hub is said by nothing now, so its ALIAS row in the i18n gate
  goes.

Type

• Fix
• Feature
• Docs
• CI / tooling
• Refactor
• Other

Verification

• npm test --prefix ui-web -- 194 files, 2695 tests, all pass

• make lint-ui -- gen:check, eslint and tsc clean (4 pre-existing
  react-hooks/exhaustive-deps warnings, none in changed files)

• npm run lint:i18n --prefix ui-tui -- generated catalogue up to date

• npm run --prefix ui-web build && python3 ui-web/build.py -- both boot
  goldens match (264 and 263 nodes)

• node ui-web/scripts/check-page.mjs, check-css.mjs,
  check-class-namespace.mjs -- all OK

• Mutation check: 14 mutations applied one at a time (each wait reverted to its
  old word or to null, each shimmer and each reduced-motion rule removed, one
  section's shape deleted so it falls through to the default). Every one turns a
  case red.

• Real browser: every wait photographed in light and dark through Playwright on
  the vite dev page, with the fixture transport's replies held open so the wait
  states stay on screen.

• Relevant tests pass locally

• Relevant lint / type checks pass locally

• User-facing docs or screenshots are updated when needed

Risk

User-visible: every settings wait changes from a word to a shape. No behaviour,
no state and no wire shape moves; what a section draws once its values are in is
unchanged. The three new bar classes are additive and scoped to their own
sheets, and all three hold still under prefers-reduced-motion.

Two changes reach past the waits: the settings store's test-only reset now
clears its in-flight load, and the i18n gate loses the gui.hub ALIAS row that
nothing measures any more.

Rollback: revert the single commit. Nothing is persisted and no generated file
other than the two boot goldens and the TUI catalogue moves.

• Security impact considered
• Backward compatibility considered
• Rollback path is clear for risky changes

Related Issues

N/A

[gloryfromca]

No blockers; this can merge as far as I am concerned.

Reviewed the complete one-commit diff against the refreshed github/main, the affected settings/two-pane/cron callers, and the relevant history. I also checked the repository rules and Web UI architecture vocabulary, backward compatibility of the replaced loading states, generated i18n and boot-golden changes, and that tests were added without weakening prior assertions.

Verification:

• focused loading-state suites: 122 passed
• full ui-web suite: 2,695 passed
• npm run type-check: passed
• npm run lint: passed with four existing hook warnings and no errors
• production build, both boot snapshots, and check-page: passed
• TUI generated i18n catalogue check: passed
• source-language, large-file, and diff-whitespace checks: passed