Accept /audio base URLs when validating ASR transcription endpoint

Some OpenAI-compatible deployments expose ASR under a base URL that already ends with /audio. ASR validation now treats that as a valid prefix and appends only /transcriptions to avoid generating /audio/audio/transcriptions.

Constraint: Keep ASR validation URL normalization conservative and backwards-compatible

Rejected: Full URL path rewrite heuristics | risk of breaking custom reverse-proxy layouts

Confidence: high

Scope-risk: narrow

Tested: cargo test -q

openless-all/app/src-tauri/src/commands.rs

@@ -300,6 +300,9 @@ fn asr_transcriptions_url(base_url: &str) -> Result<String, String> {
     if trimmed.ends_with("/audio/transcriptions") {
         return Ok(trimmed.to_string());
     }
+    if trimmed.ends_with("/audio") {
+        return Ok(format!("{trimmed}/transcriptions"));
+    }
     Ok(format!("{trimmed}/audio/transcriptions"))
 }
 
@@ -734,6 +737,10 @@ mod tests {
             asr_transcriptions_url("https://api.openai.com/v1").unwrap(),
             "https://api.openai.com/v1/audio/transcriptions"
         );
+        assert_eq!(
+            asr_transcriptions_url("https://api.openai.com/v1/audio").unwrap(),
+            "https://api.openai.com/v1/audio/transcriptions"
+        );
         assert_eq!(
             asr_transcriptions_url("https://api.openai.com/v1/audio/transcriptions").unwrap(),
             "https://api.openai.com/v1/audio/transcriptions"