Nim's C backend silently transforms large struct parameters (>16 bytes) into
pointer parameters when calling importc functions. The destroy_* functions were
declared taking T by value in Rust, but Nim always passed &T — causing Rust to
read garbage from the stack on x86-64 (SIGILL on CI) while accidentally working
on ARM64 macOS due to that ABI coincidentally also using pointers for large structs.
Fix by changing all destroy_* functions to take &mut T and using drop_in_place,
which is the correct idiom for dropping a value through a pointer.
On the Nim side, replace scattered manual destroy calls with defer, which
guarantees cleanup on all exit paths and prevents use-after-destroy bugs.
The dynlib pragma hard-coded a library path and resolved it via dlopen() at
runtime, preventing static linking and forcing a specific load-time path.
Using bare {.importc.} lets consumers choose: link liblibchat dynamically
at link time (--passL:-llibchat) or link it statically into their binary.
* Add Identity name
* Update Context to accept a name
* Change constructor in bindings
* Add name retrieval to bindings
* Update constructor string type
* Remove uneeded files
* rename functions for symmetry
