Zupt v2.1.1: fix cross-arch build issues, eliminate UB, improve Android/Termux support

- Removed all shipped .o files from tarball (fixes aarch64/Termux linker errors with x86_64 objects)
- Added arch-safety guard in Makefile to auto-detect and remove incompatible .o files
- Switched default compiler from gcc to cc (Termux uses clang)
- Skipped -lpthread on Android (bionic provides pthreads)
- Added Android detection via uname -o
- Fixed Keccak UB: ROL64(x,0) no longer expands to undefined x >> 64
- Achieved zero UBSan/ASAN issues across all PQ crypto paths
- Moved sys/syscall.h include to file scope with proper __linux__ guard

Release stats:
- 73 files, 159KB, zero .o artifacts
- 70/70 tests passing
- Fully clean under ASAN + UBSan

Note: full-disk encryption (--disk) deferred to v2.2.0 (requires raw device I/O, sparse detection, and privilege handling)

ROADMAP.md

@@ -19,7 +19,8 @@
 | **v1.5** | **✅** | **Jasmin assembly linked — CT MAC verify + ML-KEM FO select active in binary** |
 | **v1.5.5** | **✅** | **Man page install, V=1 verbose, LDFLAGS/PIE, rpmlint, multi-arch Makefile** |
 | **v2.0** | **✅** | **VaptVupt 1.1.0 codec with auto hardware detection, all 5 Jasmin wired, AVX SIGILL fix, copy_match/litlen fixes, ACSL, mlock, fuzzing, canaries, AES-NI pipeline, MT decompress, multi-arch (6 arches)** |
-| **v2.1** | **✅ Current** | **VaptVupt 1.4.0: cross-block dictionary, context prefetch, faster adaptive window, integration API** |
+| **v2.1** | **✅** | **VaptVupt 1.4.0: cross-block dictionary, context prefetch, faster adaptive window, integration API** |
+| **v2.1.1** | **✅ Current** | **Termux/Android build fix, arch-safety guard, Keccak UB fix, no stale .o in tarballs** |
 
 ## Planned