feat(02-01): add Google AI, Vertex AI, AWS Bedrock, xAI providers

- google-ai: AIzaSy pattern for Gemini
- vertex-ai: AIzaSy + Bearer verify on aiplatform endpoint
- aws-bedrock: ABSK long-token and AKIA medium patterns
- xai: xai- 80-char token pattern
- All dual-located in providers/ and pkg/providers/definitions/

providers/aws-bedrock.yaml

@@ -0,0 +1,24 @@
+format_version: 1
+name: aws-bedrock
+display_name: AWS Bedrock
+tier: 1
+last_verified: "2026-04-05"
+keywords:
+  - "ABSK"
+  - "bedrock"
+  - "aws_bedrock"
+  - "bedrock-runtime"
+  - "AKIA"
+patterns:
+  - regex: 'ABSK[A-Za-z0-9+/]{109,269}={0,2}'
+    entropy_min: 4.0
+    confidence: high
+  - regex: 'AKIA[0-9A-Z]{16}'
+    entropy_min: 3.0
+    confidence: medium
+verify:
+  method: GET
+  url: ""
+  headers: {}
+  valid_status: []
+  invalid_status: []