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

config/redbear-full.toml

@@ -133,6 +133,13 @@ redbear-meta = {}
 # Phase 1 runtime validation tests (POSIX: signalfd, timerfd, eventfd, shm_open, sem_open, waitid)
 relibc-phase1-tests = {}
 
+# Native build toolchain (Phase 3: GCC + binutils running on redox)
+# Produces gcc/g++/as/ld that execute inside Red Bear OS
+gcc-native = {}
+binutils-native = {}
+# llvm-native = {}  # suppressed: Redox C++/pthread header gaps; not needed for greeter proof
+# rust-native = {}  # suppressed: depends on llvm-native; not needed for greeter proof
+
 # Desktop fonts and icons
 dejavu = {}
 freefont = {}

config/redbear-mini.toml

@@ -89,8 +89,14 @@ iommu = {}
 bash = {}
 bottom = {}
 #curl = {}  # suppressed: nghttp2 dependency chain fails; curl not needed for boot/recovery
-#diffutils = {}  # suppressed: gnulib #include_next wrappers conflict with relibc header structure (circular stddef→stdint→sys/types→wchar→stdio chain)
+diffutils = {}
 findutils = {}
+uutils-tar = {}
+bison = {}
+flex = {}
+meson = {}
+ninja-build = {}
+m4 = {}
 #git = {}  # suppressed: cascading rebuild; git not needed for boot/recovery
 htop = {}
 #mc = {}  # suppressed: C99 format warning errors in compilation