Fix DreamMaker parent-relative #include paths (lstrip charset misuse)

`extract_dm` normalized include paths with `raw.lstrip("./")`. `str.lstrip`
treats its argument as a *set of characters*, not a prefix, so it strips
every leading `.` and `/` — destroying parent-relative includes:

    "../shared/base.dm"  -> "shared/base.dm"
    "../../a.dm"         -> "a.dm"
    ".hidden/x.dm"       -> "hidden/x.dm"

`(path.parent / norm).resolve()` then points at the wrong directory,
`.exists()` returns False, and a correct internal `imports_from` edge to the
real included file becomes a bogus external `imports` edge to a phantom node,
silently losing the cross-file link.

The sibling local-include resolver in `extractors/bash.py` resolves
`(path.parent / raw)` from the raw path without stripping `..`, confirming
the intent. Strip only a literal leading `./` (re is already imported) so
`../` includes resolve correctly; the `./`-prefix and no-prefix cases are
unchanged.

graphify/extractors/dm.py

@@ -86,7 +86,7 @@ def extract_dm(path: Path) -> dict:
             file_node = node.child_by_field_name("file")
             raw = _read_include_path(file_node)
             if raw:
-                norm = raw.replace("\\", "/").lstrip("./")
+                norm = re.sub(r"^\./", "", raw.replace("\\", "/"))
                 resolved = (path.parent / norm).resolve()
                 edge: dict = {
                     "source": file_nid,