Move tool profiles to a root file and version the release as 0.5.0

- Tool profiles come from a committed `.napseer-tools.json` at the
  project root (schema napseer.tools.v1). The unreleased tool_profiles
  field in .napseer/project.json is removed: released clients reject
  unknown locator fields, and 0.4.0 treats any extra file inside .napseer/
  as private state needing migration (a test loads the released 0.4.0
  check from c427e24 to prove the root file is invisible to it).
  Environment still overrides; unusable files warn and fall back to core.
- CLI release 0.5.0 with distribution contract 2026-09-29; the minimum
  supported contract stays 2026-09-10. The newer-contract rejection test
  now derives its date from the installer's own contract.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/test_cli_command_system.py

@@ -1,4 +1,5 @@
 import importlib.util
+import datetime
 import hashlib
 import json
 import pathlib
@@ -513,11 +514,16 @@ def test_manifest_accepts_a_future_compatible_release():
 def test_manifest_rejects_a_minimum_contract_newer_than_installer():
     module = load_installer()
     manifest, _payloads = fake_bundle(module)
-    manifest["contract"]["current"] = "2026-09-11"
-    manifest["contract"]["minimum_supported"] = "2026-09-11"
+    # One day past this installer's own contract, whatever it currently is.
+    newer = (
+        datetime.date.fromisoformat(module.CLI_DISTRIBUTION_CONTRACT_VERSION)
+        + datetime.timedelta(days=1)
+    ).isoformat()
+    manifest["contract"]["current"] = newer
+    manifest["contract"]["minimum_supported"] = newer
     for item in manifest["items"]:
-        item["contract_version"] = "2026-09-11"
-        item["minimum_contract_version"] = "2026-09-11"
+        item["contract_version"] = newer
+        item["minimum_contract_version"] = newer
 
     try:
         module.validated_manifest_items(manifest)