build(rawcli): make prompt_toolkit a core dependency + document rawcli

`pm3py rawcli` is a headline tool, so prompt_toolkit moves from the
[rawcli] extra into core dependencies — a plain `pip install` gets it and
the command just works. The extra is removed; the missing-module guard now
points at a reinstall (it only fires on a broken env).

README: add the rawcli feature bullet, a dedicated "pm3py rawcli"
section (breadcrumb, entry toggle, identify, function-style commands, live
trace, TLV, completion), prompt_toolkit in the dependency list, and cli/
in the architecture tree.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pm3py/cli/main.py

@@ -25,9 +25,8 @@ def main(argv: list[str] | None = None) -> int:
             import prompt_toolkit  # noqa: F401
         except ModuleNotFoundError:
             print(
-                "pm3py rawcli needs prompt_toolkit, which isn't installed.\n"
-                "  install it with:  pip install 'pm3py[rawcli]'\n"
-                "  or directly:      pip install prompt_toolkit",
+                "pm3py rawcli needs prompt_toolkit (a core dependency) but it isn't importable.\n"
+                "  reinstall pm3py, or:  pip install prompt_toolkit",
                 file=sys.stderr,
             )
             return 2