fix(CRITICAL): bridge build delayed binding + Docker tolerance + improved preload

build_unified_bridge.sh:
  - set -euo → set -eo (avoid unbound var failures)
  - Drop -ltorch_cuda -lc10_cuda (unavailable at Docker build time)
  - Add -Wl,--unresolved-symbols=ignore-in-shared-libs
    ixformer::infer symbols resolved at runtime via RTLD_GLOBAL preload

Dockerfile Step 6:
  - Wrap in (... || echo non-fatal) so Docker build continues if bridge fails

ix_unified.py:
  - 3-phase preload: lib*.so → _ixformer_torch*.so → remaining .so
  - All loaded with ctypes.RTLD_GLOBAL so symbols visible to bridge
  - Added /workspace and /home/dylan search paths

Verified on real machine: bridge compiles (272K), undefined symbols expected
until ixformer .so preloaded at runtime by ix_unified.py

ex_engine/build_unified_bridge.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 # build_unified_bridge.sh — Compile ix_unified_bridge.so on BI-V100
 # Uses manual compiler flags since torch.utils.cpp_extension is stripped from corex torch.
-set -euo pipefail
+set -eo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 SRC_DIR="${SCRIPT_DIR}/csrc/ilu"
@@ -34,8 +34,9 @@ $CXX -shared -fPIC -O2 -std=c++17 \
     -I"$TORCH_INC" \
     -I"$TORCH_INC2" \
     -L"$TORCH_LIB" \
-    -ltorch -ltorch_cpu -ltorch_cuda -lc10 -lc10_cuda \
+    -ltorch -ltorch_cpu -lc10 \
     -Wl,--no-as-needed,-rpath,"$TORCH_LIB" \
+    -Wl,--unresolved-symbols=ignore-in-shared-libs \
     -D_GLIBCXX_USE_CXX11_ABI=0 \
     -DTORCH_EXTENSION_NAME=ix_unified_bridge \
     "$SRC_DIR/ix_unified_bridge.cpp" \