Build options

[auhivern]

Added all build flags on the build script. The default configuration is kept if nothing is configured.

Whitelist/blacklist configuration of add-ons:

// Whitelist example (only system and pipeline add-ons are enabled)
const zflecs = b.dependency("zflecs", .{
    .custom_build = .whitelist,
    .toggle_system_addon = true,
    .toggle_pipeline_addon = true,
});

// Blacklist example (units add-on disabled, rest is enabled)
const zflecs = b.dependency("zflecs", .{
    .custom_build = .blacklist,
    .toggle_units_addon = true,
});

[Copilot]

Pull Request Overview

This PR adds comprehensive build configuration options to the zflecs build system, allowing users to customize Flecs compilation through build flags and addon selection. The system supports both whitelist and blacklist modes for addon configuration.

Key changes:

• Replaces hardcoded constants with configurable build options accessed via build_options
• Implements whitelist/blacklist addon configuration system with toggle options for each addon
• Adds extensive build flags for debug modes, floating-point precision, memory optimization, and performance tuning

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
src/zflecs.zig	Updates to use build options for constants, precision types, and debug flags instead of hardcoded values
build.zig	Adds comprehensive build option system with addon management, debug modes, and configurable constants

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[Srekel]

Thank you! Looks useful :)