refactor: daemon collectors, thin webui proxies, pure config reads

- move state collectors from lib/state.py to daemon/collectors/ (7
  modules, registration side-effect; daemon/server.py imports the
  package before the first populate())
- webui/api: new daemon_route() decorator factory in common.py
  collapses the try/except daemon-proxy boilerplate in all 8
  blueprints (rules/params/body/transform keep responses identical)
- firewall: interface-coverage invariant — config is the source of
  truth for zone interfaces (absent key = empty, no hands-off
  zones); pure validate_coverage() enforced at save (400) and apply
  (409, force: true overrides), top-level `unmanaged` exemption
- lib: get_config() reads are now pure (no dir creation or writes);
  new lib/bootstrap.py creates runtime dirs and persists the
  one-shot nginx legacy migration at daemon start, after
  system_import (lib.nginx.migrate_config_file)
- lib/common: compute_pending() apply-bookkeeping helper
- daemon: emit_and_refresh() handler helper; refresh_state(bump=) so
  /status/refresh no longer bumps versions (poll/mutation only)
- acme: move --log last so acme.sh never treats a real arg as the
  log-file argument
- docs: AGENTS.md, config.md, state-model.md, api.md updated;
  HARDEN.md dropped (plan implemented); apply-confirm force wording

Tests: 917 passed; ruff check + format clean.

tests/test_network.py

@@ -29,10 +29,11 @@ class TestGetConfig:
         assert isinstance(cfg, dict)
         assert "interfaces" in cfg
 
-    def test_creates_config_file(self, tmp_network):
+    def test_missing_file_returns_default_without_writing(self, tmp_network):
+        # Pure read: get_config never materializes the file.
         cfg = _net.get_config()
-        assert _net.CONFIG_FILE.exists()
         assert cfg["interfaces"] == {}
+        assert not _net.CONFIG_FILE.exists()
 
 
 class TestSaveConfig: