chore: name release binary av

Match the binary inside Goreleaser archives to the binary
produced by `go install .../cmd/av`. Without this, archive
extracts contain `alphavantage` while go install produces `av`.

Assisted-by: Claude:claude-opus-4-7

Author: crhntr

.goreleaser.yaml

@@ -17,6 +17,7 @@ before:
 
 builds:
   - main: ./cmd/av
+    binary: av
     env:
       - CGO_ENABLED=0
     goos: