App: Return cycle path from find_circular_deps()

The __find_circular_deps() and find_circular_deps() methods now return list[str] instead of bool. On a cycle, the path builds up the dependency chain in __find_circular_deps_recursive(), and __find_circular_deps() appends the closing project to complete the cycle. An empty list means no cycle found.
CmdDep prints the cycle as 'a -> b -> c -> a' instead of a generic message.
Assisted-by: unsloth/Qwen3.6-35B-A3B-GGUF:IQ4_NL and pi.dev
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/App.py

@@ -315,7 +315,8 @@ class App(Base):
         temp.remove(project)
         return None
 
-    def __find_circular_deps(self, projects: list[str], flavours: list[str]) -> bool:
+    def __find_circular_deps(self, projects: list[str],
+                             flavours: list[str]) -> list[str]:
         graph: Graph = {}
         ret: list[str] = []
         self.__read_dep_graph(projects, flavours, graph)
@@ -330,8 +331,9 @@ class App(Base):
             )
             if last is not None:
                 log(DEBUG, f'Found circular dependency below {project}, last is {last}')
-                return True
-        return False
+                ret.append(last)
+                return ret
+        return []
 
     def __init__(self, distro: Distro | None = None) -> None:
 
@@ -627,5 +629,5 @@ class App(Base):
             return ', '.join(intersection)
         return None
 
-    def find_circular_deps(self, projects: list[str], flavours: list[str]) -> bool:
+    def find_circular_deps(self, projects: list[str], flavours: list[str]) -> list[str]:
         return self.__find_circular_deps(projects, flavours)

src/python/jw/pkg/cmds/projects/check/CmdDep.py

@@ -1,8 +1,9 @@
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 from ....lib.log import NOTICE, log
 from .Cmd import Cmd, Parent
-from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
     from argparse import ArgumentParser, Namespace
@@ -22,8 +23,13 @@ class CmdDep(Cmd):  # export
         parser.add_argument('-f', '--flavour', nargs = '?', default = 'build')
 
     async def _run(self, args: Namespace) -> None:
-        if self.app.find_circular_deps(args.module, args.flavour):
-            log(NOTICE, f'Found circular dependency in flavour {args.flavour}')
+        cycle = self.app.find_circular_deps(args.module, args.flavour)
+        if cycle:
+            log(
+                NOTICE,
+                f'Found circular dependency in flavour {args.flavour}: '
+                ' -> '.join(cycle)
+            )
             exit(1)
         log(
             NOTICE,