feat(installer): harden database init and service setup steps

- InitDatabaseStep: create DbPath parent directory so custom paths work
- RegisterServiceStep: pass obj= argument so ServiceAccount is honoured
- StartServiceStep: poll for RUNNING state so downstream steps don't race

src/ClaudeDo.Installer/Steps/InitDatabaseStep.cs

@@ -1,3 +1,4 @@
+using System.IO;
 using ClaudeDo.Data;
 using ClaudeDo.Installer.Core;
 using Microsoft.EntityFrameworkCore;
@@ -15,6 +16,10 @@ public sealed class InitDatabaseStep : IInstallStep
             var expandedPath = Paths.Expand(ctx.DbPath);
             progress.Report($"Initializing database at {expandedPath}");
 
+            var parent = Path.GetDirectoryName(expandedPath);
+            if (!string.IsNullOrEmpty(parent))
+                Directory.CreateDirectory(parent);
+
             var options = new DbContextOptionsBuilder<ClaudeDoDbContext>()
                 .UseSqlite($"Data Source={expandedPath}")
                 .Options;