fix: address low/informational sec-parser follow-ups

- client_cli: capture errno before output_escape() in
  read_patterns_from_file() so an over-long line is still reported as
  EFBIG instead of the (possibly malloc-clobbered) errno.
- file_list: guard string_list_add() capacity doubling against
  overflow (capacity > INT_MAX / 2), matching filter_rule_list_add();
  callers already surface the false as a memory-allocation error.
- compression: ZSTD_isError() is true for ZSTD_CONTENTSIZE_UNKNOWN,
  which made the 3x unknown-size fallback dead code.  Test the
  CONTENTSIZE_ERROR/UNKNOWN sentinels explicitly so unknown-size frames
  reach the estimate path (still bounded by the existing hard limit)
  while invalid frames are rejected.  Known-size frames and the 100 MB
  ceiling/overflow checks are unchanged.
- tests: add an unknown-content-size-frame decompression test.

Tests: ./build/tests and ./build-asan/tests all pass (42/42);
clang-format + cppcheck clean.

src/shared/compression.c

@@ -243,9 +243,13 @@ Data* data_decompress_limited(Data* compressed_data, size_t maximum_size) {
   log_debug_message(LOG_DEBUG_UTIL, "Start to decompress data");
   unsigned long long dst_size =
       ZSTD_getFrameContentSize(compressed_data->data, compressed_data->size);
-  if (ZSTD_isError(dst_size)) {
-    log_message(LOG_LEVEL_ERROR, "Failed to get decompressed size: %s",
-                ZSTD_getErrorName(dst_size));
+  /* ZSTD_isError() is also true for ZSTD_CONTENTSIZE_ERROR and
+   * ZSTD_CONTENTSIZE_UNKNOWN (both are encoded near (size_t)-1), so test the
+   * sentinels explicitly instead of blanket-rejecting every error-ish value:
+   * only CONTENTSIZE_ERROR means an unreadable header, while CONTENTSIZE_UNKNOWN
+   * must reach the estimate fallback below. */
+  if (dst_size == ZSTD_CONTENTSIZE_ERROR) {
+    log_message(LOG_LEVEL_ERROR, "Failed to get decompressed size: invalid zstd frame");
     return NULL;
   }