feat: add OAuth provider abstraction for CLI configuration (#3157)

Signed-off-by: Adam Tarantino <tarantino.adam@gmail.com>

crates/goose/src/providers/githubcopilot.rs

@@ -387,7 +387,12 @@ impl Provider for GithubCopilotProvider {
             GITHUB_COPILOT_DEFAULT_MODEL,
             GITHUB_COPILOT_KNOWN_MODELS.to_vec(),
             GITHUB_COPILOT_DOC_URL,
-            vec![ConfigKey::new("GITHUB_COPILOT_TOKEN", true, true, None)],
+            vec![ConfigKey::new_oauth(
+                "GITHUB_COPILOT_TOKEN",
+                true,
+                true,
+                None,
+            )],
         )
     }
 
@@ -466,4 +471,33 @@ impl Provider for GithubCopilotProvider {
         models.sort();
         Ok(Some(models))
     }
+
+    async fn configure_oauth(&self) -> Result<(), ProviderError> {
+        let config = Config::global();
+
+        // Check if token already exists and is valid
+        if config.get_secret::<String>("GITHUB_COPILOT_TOKEN").is_ok() {
+            // Try to refresh API info to validate the token
+            match self.refresh_api_info().await {
+                Ok(_) => return Ok(()), // Token is valid
+                Err(_) => {
+                    // Token is invalid, continue with OAuth flow
+                    tracing::debug!("Existing token is invalid, starting OAuth flow");
+                }
+            }
+        }
+
+        // Start OAuth device code flow
+        let token = self
+            .get_access_token()
+            .await
+            .map_err(|e| ProviderError::Authentication(format!("OAuth flow failed: {}", e)))?;
+
+        // Save the token
+        config
+            .set_secret("GITHUB_COPILOT_TOKEN", Value::String(token))
+            .map_err(|e| ProviderError::ExecutionError(format!("Failed to save token: {}", e)))?;
+
+        Ok(())
+    }
 }