docs(b20): use Cobalt ERC-8056 multiplier interface in examples

[roethke]

What changed? Why?

Eric Brown asked that all B20 examples in docs use the new interface from the Cobalt multiplier changelog. Examples still used the Beryl names.

Beryl name (status at Cobalt per base-std)	Now used (Cobalt, ERC-8056)
updateMultiplier(uint256) (deprecated, emergency setter)	updateUIMultiplier(uint256,uint256)
multiplier() (canonical; ERC-8056 alias added)	uiMultiplier()
scaledBalanceOf(address) (canonical; ERC-8056 alias added)	balanceOfUI(address)
toScaledBalance / toRawBalance (deprecated)	toUIAmount / fromUIAmount
MultiplierUpdated (deprecated, instant setter only)	UIMultiplierUpdated

• Vibenet engine (docs/static/vibenet-engine.txt): ABI and helpers switched to updateUIMultiplier, uiMultiplier, balanceOfUI. New latestTimestamp and waitForTimestamp helpers (60s timeout). ENGINE_VERSION 4 → 5 and loader cache key ?v=4 → ?v=5, so browsers don't serve the stale engine.
• Live split demo (AssetDemo.jsx): schedules the 2-for-1 split ~15s ahead (margin for a faucet top-up, the cross-tab send lock, or a slow RPC), waits for effectiveAt, then reads uiMultiplier() and balanceOfUI(). The offline fallback shows the same calls.
• B20PlaygroundDemo.jsx: offline split uses updateUIMultiplier / UIMultiplierUpdated, and the caption says balances double at effectiveAt, not in the same call.
• Verified sample ABI (abi.ts): removed the 3 deprecated entries; no sample called them.
• List Tokenized Stocks guide: helper table now lists the ERC-8056 functions, and says which Beryl names stay canonical vs deprecated. The history section now cites UIMultiplierUpdated (the old text said MultiplierUpdated fires on scheduled updates, but it only fires on the instant setter), keys changes by effectiveAtTimestamp, and says to drop updates later cancelled by UIMultiplierUpdateCancelled.
• constants.mdx: wording uses the new names; removed an em-dash.
• upgrades/beryl/b20.mdx: table left as-is (accurate for Beryl); added a Note that maps each name to its Cobalt status and notes that the scheduled setter emits only UIMultiplierUpdated.

Notes to reviewers

• Out of scope: reference pages for the deprecated functions (eg, update-multiplier.mdx, scaled-balance-of.mdx) still document them, with deprecation warnings. apply-a-multiplier.mdx and the concept pages already lead with the new names.

• Vibenet support: confirmed on a live Vibenet token (VIBE, 0xb200…133d) that uiMultiplier, newUIMultiplier, effectiveAt, totalSupplyUI, and MAX_UI_MULTIPLIER all respond. Vibenet produces ~5–8 blocks/s with 1s timestamps, so the demo's ~15s wait is short.

• For the B20 team: deprecation status of multiplier() / scaledBalanceOf. base-std (changelog/02_Cobalt_B20Asset_multiplier.md, IB20Asset.sol) marks them "unchanged (canonical name)", with uiMultiplier() / balanceOfUI as ERC-8056 aliases. The rendered Cobalt changelog on master labeled them "deprecated-name-kept", and this PR originally repeated that. This PR now follows base-std, and docs(upgrades): rename Cobalt B20 pages, add Denim B20 upgrade pages #2025 fixes the rendered changelog table. Examples still use the ERC-8056 names per Eric's request, since both return the same values. Please confirm base-std is the intended status.

• For the B20 team: demo effectiveAt margin. updateUIMultiplier reverts EffectiveAtInPast unless effectiveAt > block.timestamp at inclusion. The demo picks effectiveAt before sending, so a slow send path can make it land late. 15s is a judgment call between reliability and how long the reader waits; a retry on EffectiveAtInPast would be the more robust option if you prefer.

How has it been tested?

• node scripts/test-vibenet-engine.mjs: passes, with a new assertion that the updateMultiplier helper is gone (re-run after review fixes: passes)
• tsc --noEmit on examples/verified-doc-samples/typescript: passes
• node scripts/validate-docs-structure.js: passes
• node scripts/lint-mdx.js: 0 errors on changed pages
• Not yet done: clicking through the live split demo in a browser preview

Screenshots

TODO: capture the Apply a Multiplier demo split step (live and offline).

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