fix(sling): use polecat path from creation instead of re-computing

When spawning a polecat via `gt sling`, the code was discarding the
return value from AddWithOptions()/RepairWorktreeWithOptions() and then
calling Get() to retrieve the polecat object. This caused Get() to
re-compute the clone path using os.Stat() checks, which fails for remote
rigs where the worktree exists on a remote machine but not locally.

This fix:
1. Uses the return value from AddWithOptions()/RepairWorktreeWithOptions()
   directly instead of calling Get() afterwards
2. Passes the correct ClonePath to the session manager via WorkDir option,
   ensuring the session starts in the right directory

This ensures consistency between worktree creation and session startup,
fixing the issue where polecats would get "not a git repository" errors
when the os.Stat() fallback logic chose the wrong path.

Fixes: gt-job89

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: furiosa

internal/cmd/polecat_spawn.go

@@ -84,6 +84,12 @@ func SpawnPolecatForSling(rigName string, opts SlingSpawnOptions) (*SpawnedPolec
 		HookBead: opts.HookBead,
 	}
 
+	// polecatObj will hold the polecat returned from Add or Repair.
+	// We use this directly instead of calling Get() afterwards, because Get()
+	// re-computes the path using os.Stat() which can fail for remote rigs.
+	// See: gt-job89 - "gt sling creates worktree in nested subdirectory"
+	var polecatObj *polecat.Polecat
+
 	if err == nil {
 		// Stale state: polecat exists despite fresh name allocation - repair it
 		// Check for uncommitted work first
@@ -96,25 +102,21 @@ func SpawnPolecatForSling(rigName string, opts SlingSpawnOptions) (*SpawnedPolec
 			}
 		}
 		fmt.Printf("Repairing stale polecat %s with fresh worktree...\n", polecatName)
-		if _, err = polecatMgr.RepairWorktreeWithOptions(polecatName, opts.Force, addOpts); err != nil {
+		polecatObj, err = polecatMgr.RepairWorktreeWithOptions(polecatName, opts.Force, addOpts)
+		if err != nil {
 			return nil, fmt.Errorf("repairing stale polecat: %w", err)
 		}
 	} else if err == polecat.ErrPolecatNotFound {
 		// Create new polecat
 		fmt.Printf("Creating polecat %s...\n", polecatName)
-		if _, err = polecatMgr.AddWithOptions(polecatName, addOpts); err != nil {
+		polecatObj, err = polecatMgr.AddWithOptions(polecatName, addOpts)
+		if err != nil {
 			return nil, fmt.Errorf("creating polecat: %w", err)
 		}
 	} else {
 		return nil, fmt.Errorf("getting polecat: %w", err)
 	}
 
-	// Get polecat object for path info
-	polecatObj, err := polecatMgr.Get(polecatName)
-	if err != nil {
-		return nil, fmt.Errorf("getting polecat after creation: %w", err)
-	}
-
 	// Resolve account for runtime config
 	accountsPath := constants.MayorAccountsPath(townRoot)
 	claudeConfigDir, accountHandle, err := config.ResolveAccountConfigDir(accountsPath, opts.Account)
@@ -134,6 +136,12 @@ func SpawnPolecatForSling(rigName string, opts SlingSpawnOptions) (*SpawnedPolec
 		fmt.Printf("Starting session for %s/%s...\n", rigName, polecatName)
 		startOpts := polecat.SessionStartOptions{
 			RuntimeConfigDir: claudeConfigDir,
+			// Use the ClonePath from the polecat object directly, rather than
+			// letting the session manager re-compute it via clonePath() which
+			// uses os.Stat(). This ensures consistency for remote rigs where
+			// the local filesystem check would fail.
+			// See: gt-job89 - "gt sling creates worktree in nested subdirectory"
+			WorkDir: polecatObj.ClonePath,
 		}
 		if opts.Agent != "" {
 			cmd, err := config.BuildPolecatStartupCommandWithAgentOverride(rigName, polecatName, r.Path, "", opts.Agent)