Parameter Packs for ECS

[ctreffs]

Description

This PR refactors Fireblade ECS to leverage Swift Parameter Packs (SE-0393), replacing the previous Sourcery-based code generation for Family types. This modernization results in a significantly smaller codebase, easier maintenance, and a more idiomatic Swift API while maintaining strict feature parity and performance.

Key Features & Improvements

• Variadic Families: Replaced Family1 through Family8 (and beyond) with a single, variadic Family<each C: Component>.
• Sequence Conformance: Restored full Sequence and IteratorProtocol support for Family, enabling the familiar for (pos, vel) in family syntax without performance degradation.
• Codable Feature Parity: Reimplemented family serialization to ensure identical JSON output structure. The FamilyMemberContainer logic has been preserved to maintain compatibility with existing serialized data.
• Unified Nexus API:
  • Nexus.family(requiresAll: ...) now accepts an arbitrary number of component types.
  • Nexus.createEntity(with: ...) now supports parameter packs for type-safe entity creation.
  • A dedicated requires: overload for single-component families has been maintained for ease of use.
• Sendable Conformance: Family, ComponentsIterator, EntityIterator, and EntityComponentIterator now conform to Sendable, improving thread safety guarantees.
• Tooling Cleanup: Removed Sourcery dependency, including .sourcery.yml, templates, and Mintfile entries.
• Documentation: Updated DocC documentation to reflect the new API and removed all broken links to deprecated generated types. Documentation analysis now passes with 0 errors.

Testing

• Migrated all existing tests to the new variadic API.
• Added a comprehensive suite of tests (FamilyTests1.swift through FamilyTests8.swift) to verify API correctness across varying component counts (1 to 8+).
• Verified Codable round-trip and feature parity with FamilyCodingTests.swift.
• All 138 tests pass successfully.

Source Impact

• Breaking Change: Family1, Family2, etc. type aliases are removed in favor of Family<C1, C2, ...>.
• Breaking Change: Deployment target bumped to macOS 14+ / iOS 17+ to support the required Swift runtime features for generic parameter packs.

Checklist

• I've read the Contribution Guidelines
• I've followed the coding style of the rest of the project.
• I've added tests covering all new code paths my change adds to the project (to the extent possible).
• I've added benchmarks covering new functionality (if appropriate).
• I've verified that my change does not break any existing tests or introduce unexpected benchmark regressions.
• I've updated the documentation (if appropriate).