Refactor and enhance OCR and API functionalities

- Removed obsolete unit tests for TTS/ASR module.
- Deleted unused sample video file.
- Introduced OCRImageWrapper component for better OCR image handling with loading, success, and failure states.
- Updated copilot plugin to improve transaction handling and added new types for better type safety.
- Enhanced web search block plugin to support streaming content updates.
- Refactored API utility functions for better error handling and consistency across requests.
- Added new configuration for OCR API endpoint.
- Consolidated SSE event parsing into a shared utility.
- Created string utility functions to reduce code duplication.
- Removed outdated test documents related to compression functionality.

src/utils/string.ts

@@ -0,0 +1,27 @@
+/**
+ * Shared string utility functions.
+ * Extracted from repeated patterns across api.js, docBlock.js, proAccept.js, proBlock.js, webSearch.js.
+ */
+
+/**
+ * Normalize line endings to Unix-style (\n).
+ * Handles \r\n (Windows), \r (old Mac), and \n (Unix).
+ */
+export function normalizeNewlines(value: string = ''): string {
+  return String(value || '').replace(/\r\n?/g, '\n')
+}
+
+/**
+ * Safely coerce any value to a non-null string.
+ * Replaces the common `String(x || '')` pattern scattered across 20+ locations.
+ */
+export function safeString(value: unknown): string {
+  return String(value ?? '')
+}
+
+/**
+ * Remove trailing slashes from a URL/path string.
+ */
+export function stripTrailingSlashes(value: string = ''): string {
+  return safeString(value).replace(/\/+$/, '')
+}