Introduce typed values, inclusive ranges, and immutable variables

[HsiangNianian]

Parent

• [RFC-0001] OneRoll Program Language v2 #7

What to build

Add the RFC-0001 runtime kinds and the RFC-0003 schema 2.0 serialization foundation for instructions and values.

Frozen contract

• Value is a closed Scalar, Text, Boolean, Values, or RollSet union.
• RollSet items are {node_id, annotations} references and always retain item_kind: scalar | text, including when empty.
• Source Values literals are flat; occurrences, grouping, and repeat may produce bounded nested Values.
• InstructionResult contains id, frame-local index, byte span, canonical text, value, nullable scalar, trace_root, and nested executions.
• Scalar projection is identity for Scalar, a checked sum for flat scalar Values and Scalar RollSets, zero for empty scalar collections, and null for all other kinds.
• ${name} and ${0} resolve from immutable environments and preserve typed values.

Acceptance criteria

• Rust types serialize exactly to the RFC-0003 schema and installed Python exposes the same decoded fields.
• Inclusive ranges, Boolean literals, nested Values, quoted strings, and empty typed collections have boundary cases.
• Variables return spanned unknown/wrong-kind errors without implicit coercion.
• Scalar arithmetic and projection use checked i64 operations.
• Instruction IDs are request-local, monotonic, and replay deterministic.
• Conformance covers every kind, projection, and invalid cross-kind operation.

Blocked by

• [RFC-0001] OneRoll Program Language v2 #7
• [RFC-0003] Typed Program Result, Roll Trace, and Error Contract #4
• Return structured parse, validation, and evaluation errors with spans #12
• Use checked i64 arithmetic for expression evaluation #17