Wave 5: Schemas command, sync command, network policy, test fixtures (bd-x15, bd-3f4, bd-1cv, bd-lx6)

- Implement schemas command with list/show modes, regex filtering, ref expansion
- Implement sync command with conditional fetch, content hash diffing, dry-run
- Add NetworkPolicy enum (Auto/Offline/OnlineOnly) with env var + CLI flag resolution
- Integrate network policy into AsyncHttpClient and fetch command
- Create test fixtures (petstore.json/yaml, minimal.json) and integration test helpers
- Fix clippy lints: derivable_impls, len_zero, borrow-after-move, deprecated API
- 192 tests passing (179 unit + 13 integration), all quality gates green

tests/fixtures/petstore.yaml

@@ -0,0 +1,144 @@
+openapi: "3.0.3"
+info:
+  title: Petstore
+  version: "1.0.0"
+  description: A minimal Petstore API for testing.
+security:
+  - api_key: []
+tags:
+  - name: pets
+    description: Pet operations
+  - name: store
+    description: Store operations
+paths:
+  /pets:
+    get:
+      operationId: listPets
+      summary: List all pets
+      tags:
+        - pets
+      parameters:
+        - name: limit
+          in: query
+          required: false
+          description: Maximum number of items to return
+        - name: offset
+          in: query
+          required: false
+          description: Pagination offset
+      responses:
+        "200":
+          description: A list of pets
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: "#/components/schemas/Pet"
+    post:
+      operationId: createPet
+      summary: Create a pet
+      tags:
+        - pets
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/NewPet"
+      responses:
+        "201":
+          description: Pet created
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Pet"
+  /pets/{petId}:
+    parameters:
+      - name: petId
+        in: path
+        required: true
+        description: The ID of the pet
+    get:
+      operationId: showPetById
+      summary: Get a pet by ID
+      tags:
+        - pets
+      responses:
+        "200":
+          description: A single pet
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Pet"
+        "404":
+          description: Pet not found
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Error"
+    delete:
+      operationId: deletePet
+      summary: Delete a pet
+      tags:
+        - pets
+      deprecated: true
+      responses:
+        "204":
+          description: Pet deleted
+  /store/inventory:
+    get:
+      operationId: getInventory
+      summary: Get store inventory
+      tags:
+        - store
+      security: []
+      responses:
+        "200":
+          description: Inventory counts
+          content:
+            application/json:
+              schema:
+                type: object
+                additionalProperties:
+                  type: integer
+components:
+  schemas:
+    Pet:
+      type: object
+      required:
+        - id
+        - name
+      properties:
+        id:
+          type: integer
+          format: int64
+        name:
+          type: string
+        tag:
+          type: string
+    NewPet:
+      type: object
+      required:
+        - name
+      properties:
+        name:
+          type: string
+        tag:
+          type: string
+    Error:
+      type: object
+      required:
+        - code
+        - message
+      properties:
+        code:
+          type: integer
+          format: int32
+        message:
+          type: string
+  securitySchemes:
+    api_key:
+      type: apiKey
+      name: X-API-Key
+      in: header