refactor(storage): add context offload root authority

[likun666661]

Summary

• Add the authenticated, interactive Storage Root write facade for the SQLite context-offload Store.
• Single-flight one writer per authentic write lease and bind that writer to one immutable limits snapshot; a second open cannot silently change owner caps or Session/workspace quotas.
• Snapshot caller-owned bytes, owner identities, and copy-reference arrays before the asynchronous lease check, so mutations after admission cannot change the accepted operation.
• Drain admitted operations during close, reject new work after close or root revocation, and serialize close/reopen so two SQLite writer handles cannot overlap for one lease.

This is a stacked, storage-only follow-up to #4159. Its base is refactor/context-offload-bounded-lifecycle; it should be rebased to main after #4159 merges.

The facade remains internal to @maka/storage in this slice. It is intentionally not published as a package subpath and not added to StorageWriterComposition until a real reader-first consumer lands, so this PR does not open the database during Host Ready or emit new durable references.

Refs #4071
Depends on #4159

Verification

• npm --workspace @maka/core run build
• npm --workspace @maka/storage run build
• NODE_NO_WARNINGS=1 node --test packages/storage/dist/__tests__/context-offload-store.test.js packages/storage/dist/__tests__/sqlite-context-offload-store.test.js — 20/20 pass
• NODE_NO_WARNINGS=1 node --test --test-reporter=dot "packages/storage/dist/**/*.test.js" — full storage suite passes
• npx biome check on all changed TypeScript files
• npm run check:asf-headers

AI use

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool and scope: OpenAI Codex contributed repository inspection, authority-boundary design, implementation, tests, and PR text. The commit includes the required Generated-by trailer.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes
• No — the new authority remains unwired to production consumers

[Astro-Han]

LGTM.