Release/904.0.0

[rarquevaux]

Explanation

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Low risk: only version/changelog updates with no runtime code changes.

Overview
Release housekeeping. Bumps the root monorepo version to 904.0.0 and bumps @metamask/transaction-pay-controller to 19.0.4.

Updates the transaction-pay-controller changelog to include the 19.0.4 release notes and adjusts the [Unreleased] comparison link accordingly.

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