fix(webview): 修复 Office 文件选择后无响应问题

ContentResolver.getType() 对 doc/docx/xls/xlsx 等 Office 文件经常
返回 "application/octet-stream" 而非精确 MIME 类型，导致 allowed
检查失败、文件被拒绝、H5 无响应。

修复：rawMime 为 null 或 application/octet-stream 时，从文件显示名
的扩展名推断精确 MIME（getMimeTypeFromExtension），使 .docx 能正确
匹配 accept 约束并进入缓存复制流程。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

sdk-webview/src/main/java/com/xuqm/sdk/webview/XWebViewView.kt

@@ -448,14 +448,28 @@ fun XWebViewView(
         // Validate that the selected file's actual MIME type is within the accepted list.
         // Some devices show extra file types in the picker (e.g. .doc when only .docx was
         // requested). Passing an unsupported type to the WebView renderer can cause a native
-        // crash. We accept the file only when its MIME type matches, or fall back to passing
-        // it through when we can't determine the type (to avoid blocking legitimate uploads).
+        // crash.
         val acceptedMimes = pendingAcceptMimes.value
-        val actualMime = context.contentResolver.getType(uri)
+        // ContentResolver returns "application/octet-stream" (or null) for most Office files
+        // from file-system / Downloads providers. Fall back to extension-based inference so
+        // .docx / .doc / .xls etc. are not incorrectly rejected.
+        val rawMime = context.contentResolver.getType(uri)
+        val actualMime: String? = if (rawMime == null || rawMime == "application/octet-stream") {
+            val name = context.contentResolver.query(
+                uri, arrayOf(OpenableColumns.DISPLAY_NAME), null, null, null
+            )?.use { cursor -> if (cursor.moveToFirst()) cursor.getString(0) else null }
+            val extMime = name?.substringAfterLast('.', "")
+                ?.lowercase(Locale.ROOT)
+                ?.takeIf { it.isNotEmpty() }
+                ?.let { ext -> MimeTypeMap.getSingleton().getMimeTypeFromExtension(ext) }
+            extMime ?: rawMime
+        } else rawMime
         val allowed = acceptedMimes.isNullOrEmpty() ||
             acceptedMimes.any { accepted ->
                 accepted == "*/*" ||
-                (actualMime != null && (actualMime == accepted || actualMime.startsWith(accepted.substringBefore("*"))))
+                actualMime == null ||   // truly unknown type — don't block
+                actualMime == accepted ||
+                actualMime.startsWith(accepted.substringBefore("*"))
             }
         if (!allowed) {
             android.util.Log.w("XWV", "Rejected file: actualMime=$actualMime not in accepted=$acceptedMimes")