Implement task tree visualization command

Add 'task tree' command to show hierarchical task structure:

Usage:
  task tree # Show all epics with their children task tree <id> #
  Show specific epic/task with children

Features: - Visual status indicators: [ ] open, [~] in-progress,
[✓] done - Shows task type: [Epic] or [Task] - Indented display
for hierarchy - Shows namespace associations

Example output:
  t-PpXWsU [Epic] [ ] Task Manager Improvements [Omni/Task.hs]
    t-PpYZt2 [Task] [ ] Implement child ID generation t-PpZGVf [Task]
    [✓] Add filtering by type and parent

Updated AGENTS.md with usage examples.

Closes task t-PpZlbL

1 files changed, 39 insertions, 0 deletions

diff --git a/Omni/Task/Core.hs b/Omni/Task/Core.hs
index 140d7dc..1a9cb2e 100644
--- a/Omni/Task/Core.hs
+++ b/Omni/Task/Core.hs
@@ -256,6 +256,45 @@ showDependencyTree tid = do
           deps = filter (\t -> taskId t `elem` depIds) allTasks
       traverse_ (\dep -> printTree allTasks dep (indent + 1)) deps
 
+-- Show task tree (epic with children, or all epics if no ID given)
+showTaskTree :: Maybe Text -> IO ()
+showTaskTree maybeId = do
+  tasks <- loadTasks
+  case maybeId of
+    Nothing -> do
+      -- Show all epics with their children
+      let epics = filter (\t -> taskType t == Epic) tasks
+      if null epics
+        then putText "No epics found"
+        else traverse_ (printEpicTree tasks) epics
+    Just tid -> do
+      -- Show specific task/epic with its children
+      case filter (\t -> taskId t == tid) tasks of
+        [] -> putText "Task not found"
+        (task : _) -> printEpicTree tasks task
+  where
+    printEpicTree :: [Task] -> Task -> IO ()
+    printEpicTree allTasks task = printTreeNode allTasks task 0
+
+    printTreeNode :: [Task] -> Task -> Int -> IO ()
+    printTreeNode allTasks task indent = do
+      let prefix = T.pack (replicate (indent * 2) ' ')
+          typeStr = case taskType task of
+            Epic -> "[Epic]"
+            WorkTask -> "[Task]"
+          statusStr = case taskStatus task of
+            Open -> "[ ]"
+            InProgress -> "[~]"
+            Done -> "[✓]"
+          nsStr = case taskNamespace task of
+            Nothing -> ""
+            Just ns -> " [" <> ns <> "]"
+      putText <| prefix <> taskId task <> " " <> typeStr <> " " <> statusStr <> " " <> taskTitle task <> nsStr
+
+      -- Find and print children (tasks with this task as parent)
+      let children = filter (\t -> taskParent t == Just (taskId task)) allTasks
+      traverse_ (\child -> printTreeNode allTasks child (indent + 1)) children
+
 -- Helper to print a task
 printTask :: Task -> IO ()
 printTask t =