fix: unify dialog layout and fix content padding issues

- Fix negative margin overflow in all dialog content areas
- Standardize dialog structure with flex-col layout
- Add consistent py-4 spacing to all content areas
- Ensure proper spacing between header, content, and footer

Affected components:
- AddProviderDialog, EditProviderDialog
- McpFormModal, McpPanel
- UsageScriptModal
- SettingsDialog

All dialogs now follow unified layout pattern:
- DialogContent: flex flex-col max-h-[90vh]
- Content area: flex-1 overflow-y-auto px-6 py-4
- No negative margins that cause content overflow

src/components/providers/forms/hooks/useTemplateValues.ts

@@ -1,5 +1,8 @@
 import { useState, useEffect, useCallback, useMemo } from "react";
-import type { ProviderPreset, TemplateValueConfig } from "@/config/providerPresets";
+import type {
+  ProviderPreset,
+  TemplateValueConfig,
+} from "@/config/providerPresets";
 import type { CodexProviderPreset } from "@/config/codexProviderPresets";
 import { applyTemplateValues } from "@/utils/providerConfigUtils";