[ShogunPanda]

Summary

Migrated Watt Admin from Watt v3 to Watt v4, updating runtime dependencies, configuration formats, startup behavior, and application metadata handling. Dashboard startup now enables metrics on the selected runtime without restarting workers or replacing existing metric options.

Changes

• Replaced Watt v3 JSON configurations with Watt v4 JavaScript configurations for the dashboard, backend, composer, frontend, and test fixtures.
• Updated runtime and service handling for Watt v4 APIs, including application URLs, serving states, and revised service schemas.
• Improved metrics collection to support disabled metrics, aggregate listening applications, preserve request statistics, and close API clients reliably.
• Added startup and integration coverage for runtime metrics activation and Watt v4 behavior.
• Raised the minimum Node.js version to 24.20.0 and pinned Watt dependencies to the v4 prerelease packages.

Notes

The pinned Watt prerelease does not yet include the metrics API; integration testing currently requires packages built from platformatic/platformatic#5238, and the dependency versions should be updated before merging.

Additional Informations

AI-assisted work. All changes reviewed by a human.

[mcollina]

We need a separate next/watt-4 branch where to land this.

[ShogunPanda]

@mcollina Done, it now lands on watt-4 branch, which is a cut-off of main.
Is everything else good?

[mcollina]

lgtm once CI is green