chore(workbench): rebase onto main

[gu-stav]

Description

Rebase feat/workbench onto latest main (currently 2 commits ahead: #1128 CI cache scoping by RUNNER_OS, #1084 page-builder template).

Used git rebase --rebase-merges origin/main to preserve the prior merge structure; rerere auto-resolved the previous conflict resolutions on extractManifest.ts and commands/manifest/extract.ts (both now import SchemaExtractionError from @sanity/cli-build/_internal per #1120).

Once merged, feat/workbench should have no outstanding conflicts with main.

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Note

High Risk
Large, cross-cutting changes to sanity dev/build, filesystem locks, and Windows process detection; misbehavior could break local development or leave stale locks, though coverage is extensive.

Overview
This branch lands experimental federation + workbench support across the Sanity CLI, rebased onto current main (CI cache + page-builder template changesets included).

CLI config & paths: @sanity/cli-core adds optional federation.enabled, getCliConfigUncached for dev-time reloads of sanity.cli, and shared getSanityConfigDir / getSanityDataDir (staging-aware) for user config vs runtime state.

Build: When federation is on, builds use @sanity/federation via Vite createBuilder, merge user vite config without finalizeViteConfig, skip the usual .sanity/runtime client bundle, and skip auto-update import maps. Vite gains federation/typegen plugin wiring, strictPort: false, and optional reactRefreshHost.

Dev: devAction orchestrates a singleton workbench Vite server (lock + ~/.sanity/dev-servers registry with PID-reuse checks, including Windows PowerShell), bumps the studio/app to the next port, registers local apps with inlined manifests, and drops the old dashboard URL fetch (getDashboardAppURL removed). Init/e2e tests use --no-federation where needed.

Supporting: @sanity/federation dependency, federated-studio fixture, manifest extraction split (extractCoreAppManifest), many unit tests, snapshot workflow temporarily targeting feat/workbench / workbench dist-tag, and a large set of changeset entries documenting prior workbench PRs.

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