cub: full AUR package manager + Phase 1-5 native build tools

cub redesign (local/recipes/system/cub/):
- AUR RPC v5 client (serde_json) with search/info
- ~/.cub/ user-local recipe/source/repo storage
- Enhanced PKGBUILD parser: optdepends, .SRCINFO, split packages, 19 linuxism patterns
- Recipe generation: host: prefix on dev-deps, shallow_clone, cargopath, installs, optional-packages
- Dependency resolver: scans build errors for missing commands/headers/libs/pkgconfig, maps to packages
- Dependency installation: checks installed packages, fetches AUR deps, interactive prompt
- ~110 Arc→Redox dependency mappings
- ratatui TUI: search, info, install, build, query views
- 14 Arch-style CLI switches (-S/-Si/-Syu/-G/-R/-Q/-Qi/-Ql)
- 65 tests, 0 failures, clean build

Phase 1-5 native build tools (local/recipes/dev/):
- P1 Substrate: tar, m4, diffutils (gnulib bypass), mkfifo kernel patch (1085 lines)
- P2 Build Systems: bison, flex, meson (standalone wrapper), ninja-build, libtool
- P3 Native GCC: gcc-native, binutils-native (cross-compiled for redox host)
- P4 Native LLVM: llvm-native (clang + lld from monorepo)
- P5 Native Rust: rust-native (rustc + cargo)
- Groups: build-essential-native, dev-essential expanded

Config:
- redbear-mini: +7 tools (diffutils, tar, bison, flex, meson, ninja, m4)
- redbear-full: +4 native tools (gcc, binutils, llvm, rust)
- All recipes moved to local/ with symlinks for cookbook discovery (Red Bear policy)

Docs:
- BUILD-TOOLS-PORTING-PLAN.md: phased porting roadmap
- CUB-WORKFLOW-ASSESSMENT.md: gap analysis and integration assessment

local/recipes/system/cub/source/cub-lib/src/converter.rs

@@ -93,6 +93,7 @@ pub fn convert_pkgbuild(content: &str) -> Result<ConversionResult, CubError> {
             original_pkgbuild: content.to_string(),
             conversion_status: status.clone(),
             target: "x86_64-unknown-redox".to_string(),
+            split_packages: Vec::new(),
         },
         policy: PolicySection::default(),
     };