Fix merger rules of policies group issue

[FrozenLemonTee]

PR changes:

• Include changes in Add compound assignment and ThreeWayCompare operations with tests #11
• Fix merger rules of policies group issue in Add compound assignment and ThreeWayCompare operations with tests #11
• Impl cross type overload versions of member functions in primitive and free functions in operation

[Copilot]

Pull request overview

This PR updates the primitives framework’s policy resolution/negotiation rules and expands the operations surface to support mixed primitive/underlying operands, adding ThreeWayCompare and compound-assignment support alongside additional compile-time consistency checks.

Changes:

• Enforce “policy group” consistency after default completion (value/type/error/concurrency) and tighten type negotiation rules (non-void common_rep, compatible requires same underlying category).
• Add mixed operand overloads for operations (primitive ↔ underlying), add ThreeWayCompare, and implement compound assignment operators via dispatcher-based apply_assign.
• Add cross-underlying constructors/assignments/store/CAS for primitive, and refactor exported trait APIs (traits → meta, primitive_traits → meta::traits).

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tests/basic/test_templates.cpp	Adds custom underlying/common-rep test cases, including a void common-rep scenario.
tests/basic/test_operations.cpp	Adds tests for cross-underlying construction/store/CAS, mixed operand operations, three-way compare, and compound assignment.
src/primitive/traits.cppm	Refactors exported primitive traits into mcpplibs::primitives::meta.
src/primitive/impl.cppm	Implements cross-underlying primitive constructors/assignments/store/CAS and adds an explicit disabled underlying::traits specialization for primitive.
src/policy/utility.cppm	Centralizes resolve_policy_t with “at most one policy per category” enforcement.
src/policy/impl.cppm	Tightens type-policy checks (same category for compatible, non-void common rep) and adds integral narrowing helper.
src/operations/operators.cppm	Adds mixed operand overloads, three-way compare API, and compound-assignment implementation.
src/operations/invoker.cppm	Implements three-way compare evaluation and binds it for all value policies.
src/operations/impl.cppm	Introduces the ThreeWayCompare operation tag and traits.
src/operations/dispatcher.cppm	Switches to meta::traits, enforces policy-group consistency, and asserts non-void common rep when allowed.
.github/prompts/plan-policyBehaviorProtocol.prompt.md	Updates the design/plan document to match the new constraints and overload goals.
.github/copilot-instructions.md	Minor documentation update referencing the prompts directory.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 8 comments.