Implement minimal depmod-compatible applet for vx

- Added depmod.cpp to scan kernel module ELF files, read .modinfo, and emit metadata files.
- Implemented functionality to write binary trie indexes for libkmod/modprobe.
- Introduced command-line options for module processing.
- Created test script test_depmod.sh to verify help and version commands.

README.md

@@ -14,6 +14,7 @@ It bundles a growing set of FreeBSD-derived userland tools into a single `vx` bi
 - `find`
 - `xargs`
 - `lspci`, `setpci`
+- `depmod`
 
 ## Build
 
@@ -47,4 +48,4 @@ or via installed symlinks such as `grep`, `find`, or `patch`.
 ## Notes
 
 - The project force-includes `src/compat-headers/compat.h` to provide Linux compatibility shims for BSD userland code.
-- Some behavior is intentionally BSD-flavored, even where GNU tools differ.
+- Some behavior is intentionally BSD-flavored, even where GNU tools differ.