Add XIC v1 Engine — Execute-In-Compressed Runtime Integration

- Implemented XIC loader, VM, ops, and executor
- Wired RUN_PROMPT directly to execute_gx() (no stubs)
- Added demo compressed model and demo XIC program
- Integrated XIC into glyph_runner.py with --xic flag and shell support
- Added full validation suite and XIC_INTEGRATION_REPORT.md
- Verified real GSZ3 decompression and execution pipeline

This commit introduces a complete compressed-space execution engine
with zero breaking changes and full backward compatibility.

programs/hello_model.py

@@ -0,0 +1,4 @@
+# Simple test model for XIC
+print("Hello from XIC compressed model!")
+print(f"Greeting the universe from inside the compression engine...")
+result = "XIC execution successful"