feat: session lifecycle wrapper with manifest capture and session logging

Refactor new/resume/open to use session.Run() which wraps child process launch with pre/post manifest capture and append-only session logging to logs/sessions.log. Bump version to 0.2.0.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/open.go

@@ -7,7 +7,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/warrenronsiek/ctask/internal/config"
-	"github.com/warrenronsiek/ctask/internal/shell"
+	"github.com/warrenronsiek/ctask/internal/session"
 	"github.com/warrenronsiek/ctask/internal/workspace"
 )
 
@@ -40,6 +40,12 @@ func runOpen(cmd *cobra.Command, args []string) error {
 
 	envVars := config.EnvVars(ws.Meta.Slug, ws.Meta.Mode, root, ws.Path, ws.Meta.Category)
 
-	// Spawn interactive subshell (not agent, not cd in parent)
-	return shell.ExecShell(ws.Path, envVars, ws.Meta.Slug, ws.Meta.Mode)
+	return session.Run(session.LaunchOpts{
+		WsDir:   ws.Path,
+		EnvVars: envVars,
+		Agent:   ws.Meta.Agent,
+		Mode:    ws.Meta.Mode,
+		Slug:    ws.Meta.Slug,
+		Shell:   true, // open always launches shell
+	})
 }