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- Removed outdated test documents related to compression functionality.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/fetch.js

@@ -0,0 +1,54 @@
+/**
+ * Unified safeFetch wrapper for API requests.
+ * Handles authentication headers, credentials, and error mapping consistently across all endpoints.
+ */
+
+import { API_KEY } from './config.js'
+
+/** Build headers for JSON API requests with optional X-API-Key */
+function buildHeaders(extra = {}) {
+  return API_KEY
+    ? { 'X-API-Key': API_KEY, ...extra }
+    : { ...extra }
+}
+
+/** Parse JSON response from fetch result, handling non-OK status codes */
+async function parseJsonResponse(res) {
+  if (!res.ok) {
+    let message = `HTTP ${res.status}`
+    try {
+      const data = await res.json()
+      message = data.detail || data.error || message
+    } catch {
+      const text = await res.text()
+      if (text) message = text
+    }
+    throw new Error(message)
+  }
+  return res.json()
+}
+
+/**
+ * Fetch wrapper that handles:
+ * - Authentication headers (X-API-Key)
+ * - Credentials (include cookies)
+ * - Error mapping (HTTP status → meaningful message)
+ */
+export async function safeFetch(url, options = {}) {
+  const headers = buildHeaders(options.headers || {})
+  const res = await fetch(url, {
+    ...options,
+    headers,
+    credentials: 'include',
+  })
+
+  if (!res.ok) {
+    const errorText = await res.text()
+    throw new Error(`HTTP ${res.status}: ${errorText}`)
+  }
+
+  return res
+}
+
+/** Export helper functions for use in other modules */
+export { buildHeaders, parseJsonResponse }