feat: writing logs to the filesystem with rotation support (#1299)

* refactor: move lib/policy/config to lib/config

Signed-off-by: Xe Iaso <me@xeiaso.net>

* refactor: don't set global loggers anymore

Ref #864

You were right @kotx, it is a bad idea to set the global logger
instance.

Signed-off-by: Xe Iaso <me@xeiaso.net>

* feat(config): add log sink support

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: update spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore(test): go mod tidy

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: update spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* docs(admin/policies): add logging block documentation

Signed-off-by: Xe Iaso <me@xeiaso.net>

* docs: update CHANGELOG

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(cmd/anubis): revert this change, it's meant to be its own PR

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: go mod tidy

Signed-off-by: Xe Iaso <me@xeiaso.net>

* test: add file logging smoke test

Assisted-by: GLM 4.6 via Claude Code
Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix: don't expose the old log file time format string

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>

lib/config/testdata/good/thresholds.yaml

@@ -0,0 +1,38 @@
+bots:
+  - name: simple-weight-adjust
+    action: WEIGH
+    user_agent_regex: Mozilla
+    weight:
+      adjust: 5
+
+thresholds:
+  - name: minimal-suspicion
+    expression: weight < 0
+    action: ALLOW
+  - name: mild-suspicion
+    expression:
+      all:
+        - weight >= 0
+        - weight < 10
+    action: CHALLENGE
+    challenge:
+      algorithm: metarefresh
+      difficulty: 1
+      report_as: 1
+  - name: moderate-suspicion
+    expression:
+      all:
+        - weight >= 10
+        - weight < 20
+    action: CHALLENGE
+    challenge:
+      algorithm: fast
+      difficulty: 2
+      report_as: 2
+  - name: extreme-suspicion
+    expression: weight >= 20
+    action: CHALLENGE
+    challenge:
+      algorithm: fast
+      difficulty: 4
+      report_as: 4