docs(b20): move seize surface out of the beryl changelog entry

[youssefea]

What changed? Why?

Closes Base Knowledge Base gap gap-20261001-recover-funds-entry-says-seizewithmemo-not (gaps log, DEVREL-859). Question: "Is seizeWithMemo now available on mainnet, and should the guide and index be updated?"

The Recover Funds guide already says seizeWithMemo shipped with Cobalt. The B20 changelog's Beryl entry still contradicted it: it listed seizeWithMemo, six policy scopes (including the seize scopes), the SEIZE pause feature, and seize memo variants under Beryl, and it marked burnBlocked deprecated at Beryl. This PR corrects the Beryl entry in docs/specifications/b20/changelog.mdx:

• Four policy scopes at Beryl (transfer sender, receiver, executor, and mint receiver)
• Memo variants of transfer, transferFrom, mint, and burn only
• PausableFeature at Beryl: TRANSFER, MINT, and BURN
• burnBlocked and BURN_BLOCKED_ROLE listed as added at Beryl, not deprecated
• A pointer to the Cobalt seize entry for seizeWithMemo, the SEIZE pause feature, the seize policy scopes, and the burnBlocked deprecation

Notes to reviewers

Primary sources:

• Beryl surface (four policy getters, PausableFeature without SEIZE, burnBlocked, memo variants without seize): base/base crates/common/precompiles/src/common/abi/v1.rs
• Seize surface, SEIZE=3 pause ordinal, two new policy slots, and burnBlocked deprecated but still callable at Cobalt: docs/base-chain/specs/reference/b20/changelog/02-cobalt-b20-seize.mdx (master)
• Pause feature activation per hardfork: docs/specifications/b20/concepts/roles-and-pause.mdx (master)
• Cobalt Mainnet activation (2026-09-30): docs/upgrades/cobalt/overview.mdx and the Cobalt table already in the changelog

This replaces the B20 changelog part of #2092 for this gap. The other files in #2092 are out of scope here.

No SME confirmation needed. The Beryl entry still lists UNION and INTERSECT policy types, while the Cobalt table lists composite policies as a Cobalt change. That is a separate gap and is not changed here.

How has it been tested?

• node scripts/lint-mdx.js --files-from=<changed files>: passed, 0 errors, 0 warnings
• node scripts/validate-docs-structure.js: reports 2 redirect errors for /upgrades/denim/eip-8130. These also fail on master and are unrelated to this change
• The new internal link /base-chain/specs/reference/b20/changelog/02-cobalt-b20-seize exists in docs/docs.json and as a file

Screenshots

N/A (text-only change)

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[cb-heimdall]

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[linear]

DEVREL-859