Update CLI lint schema to v1.2 (v0.5 schema blocks v1.x docs)

[alpha912]

Problem

The CLI lint command uses omniscript-core/cli/schema/osf.schema.json, which is still v0.5. This causes osf lint to fail valid v1.x documents (chart/diagram/code/table/include).

Evidence

• omniscript-core/cli/src/commands/lint.ts loads schema from cli/schema/osf.schema.json.
• Spec is now v1.2 (omniscript-core/spec/v1.2/README.md).

Expected

• Update schema to v1.2 (or align to current stable spec).
• Ensure CLI lint passes valid v1.x documents.
• Update/extend lint tests accordingly.

Acceptance Criteria

• Schema includes v1.0/v1.1/v1.2 blocks and directives.
• osf lint works on v1.x examples without false errors.
• Tests updated for new schema coverage.