Add CUB package builder and include in all Red Bear OS configs

CUB (Red Bear OS Package Builder) is a Rust CLI tool that combines package management and building:
- RBPKGBUILD parser (TOML format) with full spec support
- Cookbook adapter converting RBPKGBUILD to recipe.toml
- PKGBUILD (Arch AUR) to RBPKGBUILD conversion with Linuxism detection
- Dependency mapping (Arch to Redox names)
- pkgar package creation integration
- Build environment setup with Cookbook env vars
- CLI with pacman-style shortcuts: -S, -Ss, -B, -G, -Pi, -Sua, -Sc, --import-aur

28 cub-lib tests passing. cub-cli compiles with local pkgutils.
Added cub = {} to redbear-desktop, redbear-full, redbear-minimal configs.
Created recipe symlink and updated integrate-redbear.sh.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

local/recipes/system/cub/source/cub-cli/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "cub-cli"
+default-run = "cub"
+description = "Red Bear OS Package Builder CLI"
+
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[[bin]]
+name = "cub"
+path = "src/main.rs"
+
+[dependencies]
+cub-lib = { path = "../cub-lib" }
+redox-pkg = { path = "../../../../../../recipes/core/pkgutils/source/pkg-lib", default-features = false, features = ["indicatif"] }
+clap = { workspace = true }
+termion = "4.0.6"