feat(roles): simplify roles to only Viewer, Editor, Admin

┌────────┬──────┬─────────┬────────┬────────┬───────┬────────┐
  │  Role  │ read │ comment │ create │ update │ share │ delete │
  ├────────┼──────┼─────────┼────────┼────────┼───────┼────────┤
  │ viewer │  ✓   │         │        │        │       │        │
  ├────────┼──────┼─────────┼────────┼────────┼───────┼────────┤
  │ editor │  ✓   │    ✓    │   ✓    │   ✓    │       │        │
  ├────────┼──────┼─────────┼────────┼────────┼───────┼────────┤
  │ admin  │  ✓   │    ✓    │   ✓    │   ✓    │   ✓   │   ✓    │
  └────────┴──────┴─────────┴────────┴────────┴───────┴────────┘

tests/api/grants.hurl

@@ -150,7 +150,7 @@ jsonpath "$[?(@.resource.id=='{{shared_folder_id}}')].permission" == "read"
 
 
 # ─────────────────────────────────────────────────────────────
-# Step 9 — Promote Bob to Manager (adds comment, create, update, share).
+# Step 9 — Promote Bob to Admin (adds comment, create, update, share, delete).
 #           PUT /api/grants/role reconciles the row set in one call.
 # ─────────────────────────────────────────────────────────────
 PUT {{base_url}}/api/grants/role
@@ -159,12 +159,12 @@ Content-Type: application/json
 {
   "subject":  { "type": "user",   "id": "{{dave_user_id}}" },
   "resource": { "type": "folder", "id": "{{shared_folder_id}}" },
-  "role": "manager"
+  "role": "admin"
 }
 
 HTTP 200
 [Asserts]
-jsonpath "$" count == 5
+jsonpath "$" count == 6
 
 
 # ─────────────────────────────────────────────────────────────
@@ -173,7 +173,7 @@ jsonpath "$" count == 5
 PUT {{base_url}}/api/folders/{{shared_folder_id}}/rename
 Authorization: Bearer {{dave_token}}
 Content-Type: application/json
-{ "name": "renamed-by-bob-as-manager" }
+{ "name": "renamed-by-bob-as-admin" }
 
 HTTP 200
 
@@ -192,7 +192,7 @@ HTTP 200
 
 
 # ─────────────────────────────────────────────────────────────
-# Step 12 — Bob re-shares to Carol (he has Share via Manager).
+# Step 12 — Bob re-shares to Carol (he has Share via Admin).
 # ─────────────────────────────────────────────────────────────
 POST {{base_url}}/api/grants
 Authorization: Bearer {{dave_token}}