[+] apps/network module: settings singleton, net_t helpers, CLI integration
1. add apps/network/settings.py: net_settings_t pydantic-settings singleton
with timeout (8s default) and max_size (50MB default), env vars
ARCHLINUX_NET_TIMEOUT/ARCHLINUX_NET_MAX_SIZE, reset() classmethod;
2. add apps/network/base.py: net_t class with fetch_url, fetch_text,
head_content_length, post_json, download_to_file (sync) and async
wrappers, all enforcing timeout and max_size from settings;
3. add apps/network/cli.py: net_cli_t with add_arguments/extract/apply
for --net-timeout and --net-max-size CLI args;
4. refactor cve/base.py: remove duplicate _fetch_url/_post_json/_head
wrappers, callers use net_t directly;
5. refactor cve/nvd.py, cve/osv.py, cve/arch_tracker.py: use net_t;
6. refactor pacman/client.py, pacman/manager.py: use net_t;
7. add test_network.py with settings, read_limited, fetch, cli tests;
LLM
8079aae41c