feat(sync): keep project lists device-local

[vastsa]

Why

This publishes the one local-only deliverable that was sitting on the local
main branch and never reached remote main: project lists describe the
workspace of a particular device, so portable configuration sync must not
recreate them on another device. Until now projects was still a public
ConfigSyncCategory, so a synced or restored vault could register unwanted
workspaces on the receiving machine.

The rest of that local branch (chore(sync) integration commits and the merge
commit) contains only content that remote main already has in a newer form, so
this branch publishes the feature commit alone, rebased onto current main.

Change

• Remove projects from CONFIG_SYNC_CATEGORIES, the category UI, the adapter
  registry, capture, and application; normalize saved and draft category
  selections to the supported set.
• Ignore retired projects entities in existing vault revisions and local
  recovery state, after the revision has been validated and authenticated in
  full, so local projects and supported configuration history survive an
  upgrade.
• Keep project-scoped MCP, skills, instructions, memory, and automation
  mappings working through their logical identities and explicit local folder
  mappings. Local project records and remote revision history stay intact, and
  no project deletions are published to retire the category.
• New ADR docs/adr/device-local-project-lists-in-config-sync.md (plus its
  zh-CN mirror and index entry), and the updated
  03-runtime/22-config-sync.md / 06-delivery/04-e2e-test-plan.md in both
  locales.

Consumers of ConfigSyncCategory must stop requesting projects. Existing
encrypted vaults keep validating; older clients may still publish project
entities, and new clients ignore them. Process ownership, encryption, and
approval boundaries are unchanged, and no data is deleted.

Validation

Base origin/main 9d3273fd9; candidate 6c5bdae19.

• cargo test -p host-core --locked → 823 passed, 0 failed (includes
  legacy_project_revision_sync_and_restore_preserve_local_projects and the
  config-sync S3 suite).
• cargo fmt --check -p host-core clean; cargo clippy -p host-core --all-targets reports only the two pre-existing transcripts.rs warnings
  that this change does not touch.
• Desktop suite node --test test/*.test.mjs → 3788 passed, 0 failed, including
  the new config-sync-form / config-sync-preferences / config-sync-user-path
  cases.
• tsc -p tsconfig.json --noEmit clean. (In a worktree that reuses the host
  build artifacts, the linked packages/shared/dist is stale; resolving
  @pi-desktop/shared to this branch's source reproduces the CI arrangement and
  the check passes. CI builds the packages before typechecking.)
• packages/shared vitest → 1236 passed; packages/i18n vitest → 30 passed.
• biome lint clean; check-locales (85 pairs) and check-docs (569 pages)
  pass.

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