Remove Warp cloud features and OpenTelemetry

Settings cleanup:
- Remove billing_and_usage, main_page, referrals_page, show_blocks_view,
  environments_page, handoff_environment_creation_modal,
  custom_inference_modal, remove_custom_endpoint_confirmation_dialog,
  transfer_ownership_confirmation_modal, delete_environment_confirmation_dialog
- Remove SettingsSection variants: Account, BillingAndUsage, Referrals,
  SharedBlocks, CloudEnvironments, OzCloudAPIKeys
- Remove SettingsPageViewHandle variants: Main, BillingAndUsage, Referrals,
  CloudEnvironments, OzCloudAPIKeys, SharedBlocks
- Add Platform variant for PlatformPageView
- Gut custom inference endpoint UI from ai_page.rs
- Gut transfer ownership modal from teams_page.rs
- Stub environment_management_pane as dead code
- Remove create_discount_badge usage
- Remove handle_experiment_change call

OpenTelemetry removal:
- Remove opentelemetry, opentelemetry-http, opentelemetry-otlp,
  opentelemetry_sdk, tracing-opentelemetry dependencies
- Replace tracing module with no-op stub
- Delete native.rs and cloud_agent_auth.rs

Bug fixes (prior work):
- Fix apply_diffs() to use markdown_unescaped(ctx)
- Fix notebook executor AIDocumentId handling
- Fix margin/corner-radius consistency in requested_command.rs
- Add document tool handlers to extract_tool_result_content()
- Fix deprecated from_byte_stream in MCP SSE transport
- Fix Cargo.toml profile package spec
- Upgrade rust-toolchain to 1.94.1

app/src/ai/blocklist/prompt/prompt_alert.rs

@@ -392,7 +392,7 @@ impl View for PromptAlertView {
             text_fragments.push(FormattedTextFragment::plain_text("  "));
             text_fragments.push(FormattedTextFragment::hyperlink_action(
                 "Add credits",
-                WorkspaceAction::ShowSettingsPage(SettingsSection::BillingAndUsage),
+                WorkspaceAction::ShowSettingsPage(SettingsSection::About),
             ));
         } else {
             self.action_hyperlink(&state, &mut text_fragments, app);