Fix fuzz tests for Wave 7 INET refactoring and include in test runner

The fuzz tests in test_update_message_integration.py were using the old
INET constructor pattern (INET(AFI, SAFI, Action)) which broke after
Wave 7 refactored INET to use packed-bytes-first pattern.

Changes:
- Add create_inet_nlri() helper using INET.from_cidr() factory method
- Update all 18 failing tests to use the new helper
- Update qa/bin/test_everything to run fuzz tests alongside unit tests
  (matching CI behavior: pytest ./tests/unit/ ./tests/fuzz/)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: thomas-mangin

qa/bin/test_everything

@@ -140,7 +140,7 @@ def run_command(cmd: str, env: dict | None = None, shell: bool = True) -> tuple[
 TEST_COMMANDS: dict[str, str | list[str]] = {
     'ruff-format': 'uv run ruff format src tests',
     'ruff-check': 'uv run ruff check src qa tests',
-    'unit': 'env exabgp_log_enable=false uv run pytest ./tests/unit/ -q',
+    'unit': 'env exabgp_log_enable=false uv run pytest ./tests/unit/ ./tests/fuzz/ -q',
     'config': './sbin/exabgp configuration validate -nrv ./etc/exabgp/conf-ipself6.conf',
     'no-neighbor': './qa/scripts/test_no_neighbor.py',
     'encode-decode': './qa/scripts/test_encode_decode.py',