Support for systems without dynamic memory allocation

[embeddedk8]

Problem
The library relies on standard STL containers, which perform dynamic memory allocations.
As a result, the library cannot be used in heapless embedded environments, where dynamic allocation is prohibited or unavailable.

Solution
Add support for running the library with zero heap allocations.
This could be done in two possible ways:

1. Add a compile-time option (e.g., DISABLE_HEAP)
   When enabled, the library would use alternative containers that do not allocate from the heap.

2. Use a heapless design everywhere
   If a heapless implementation works well and does not reduce performance or features, it might replace the current STL-based version completely.
   The pros and cons of keeping both versions should be evaluated.