chore(knip): register tool-fs e2e tests as knip entry points

The new packages/fs/tool-fs/tests/*.e2e.ts (+ its harness.ts) need an explicit
knip workspace entry — mirroring the other e2e-bearing packages — so knip
follows them and does not flag the files or their dsh-agent-loop/dsh-llm-deepseek
devDeps as unused.

knip.json

@@ -44,6 +44,10 @@
     "packages/subagent/subagent-acp": {
       "entry": ["tests/**/*.spec.ts", "tests/**/*.e2e.ts", "tests/mock-acp-server.ts"],
       "project": ["src/**/*.ts", "tests/**/*.ts"]
+    },
+    "packages/fs/tool-fs": {
+      "entry": ["tests/**/*.spec.ts", "tests/**/*.e2e.ts"],
+      "project": ["src/**/*.ts", "tests/**/*.ts"]
     }
   }
 }