[orm #2] Publish @universal-orm/core + universal-schema (core, together)

[suleimansh]

Part of #64. Blocked by #66.

Graduate the engine and schema together — the spike (#65) proved they cannot split: orm's and orm-memory's test suites build fixtures with defineSchema/mergeSchemas, so schema must come with the core.

Scope:

• @universal-orm/core -> @gemstack/orm, @vike-data/universal-schema -> @gemstack/schema
• Copy + rename (spike spike: graduate the data layer to @gemstack/orm (+ adapters + schema) [#64 Phase 0, not for merge] #65 already does this); preserve the JS-src-direct model
• Drop private: true, reset both to a fresh 0.x
• Publish to npm

Acceptance: @gemstack/orm + @gemstack/schema live on npm, tests green in the gemstack workspace.

[suleimansh]

Re-scope per #66: the engines stay under @universal-orm rather than graduating to @gemstack/*. This issue no longer proceeds as a rename. If/when these go public it will be under @universal-orm, not a @gemstack name. Holding on the final #66 confirmation.

[suleimansh]

Final per #66 (closed): the whole set stays @universal-orm. This issue is no longer a @gemstack rename. Re-scoped to: if/when the core + schema go public, publish them under @universal-orm (fresh 0.x + changeset), no name change. Keeping open as the publish-tracking issue under the corrected scope.

[suleimansh]

Moot here per #66: no @gemstack rename, and the @universal-orm engines live in vike-data, not this repo (removed in PR #74). If/when core + schema are published under @universal-orm, that is tracked in vike-data.