Auto-archive worktrees after PR merge (#1004)

Add a daemon setting `autoArchiveAfterMerge` (default off). When on, the
daemon's existing GitHub poll triggers archive once the PR is merged,
but only if the worktree is clean (not dirty, not ahead of origin).
Skips silently otherwise.

packages/server/src/shared/messages.ts

@@ -110,6 +110,7 @@ export const MutableDaemonConfigSchema = z
       })
       .passthrough(),
     providers: z.record(z.string(), MutableDaemonProviderConfigSchema).default({}),
+    autoArchiveAfterMerge: z.boolean().default(false),
   })
   .passthrough();
 
@@ -119,6 +120,7 @@ export const MutableDaemonConfigPatchSchema = z
     providers: z
       .record(z.string(), MutableDaemonProviderConfigSchema.partial().passthrough())
       .optional(),
+    autoArchiveAfterMerge: z.boolean().optional(),
   })
   .partial()
   .passthrough();