test: strengthen coverage for sessions, logging, and update check (#686)

## ℹ️ Description
* Strengthen the session/logging/update-check tests to exercise real
resources and guards while bringing the update-check docs in line with
the supported interval units.
- Link to the related issue(s): Issue #N/A

## 📋 Changes Summary
- Reworked the `WebScrapingMixin` session tests so they capture each
`stop` handler before the browser reference is nulled, ensuring cleanup
logic is exercised without crashing.
- Added targeted publish and update-check tests that patch the async
helpers, guard logic, and logging handlers while confirming
`requests.get` is skipped when the state gate is closed.
- Updated `docs/update-check.md` to list only the actually supported
interval units (up to 30 days) and noted the new guard coverage in the
changelog.

### ⚙️ Type of Change
- [x] 🐞 Bug fix (non-breaking change which fixes an issue)
- [ ] ✨ New feature (adds new functionality without breaking existing
usage)
- [ ] 💥 Breaking change (changes that might break existing user setups,
scripts, or configurations)

## ✅ Checklist
- [x] I have reviewed my changes to ensure they meet the project's
standards.
- [x] I have tested my changes and ensured that all tests pass (`pdm run
test`).
- [x] I have formatted the code (`pdm run format`).
- [x] I have verified that linting passes (`pdm run lint`).
- [x] I have updated documentation where necessary.

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Tests**
* Expanded test coverage for publish workflow orchestration and update
checking interval behavior.
* Added comprehensive browser session cleanup tests, including
idempotent operations and edge case handling.
* Consolidated logging configuration tests with improved handler
management validation.
  * Refined test fixtures and assertions for better test reliability.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

tests/unit/test_update_checker.py

@@ -5,6 +5,7 @@
 from __future__ import annotations
 
 import json
+import logging
 from datetime import datetime, timedelta, timezone, tzinfo
 from typing import TYPE_CHECKING
 from unittest.mock import MagicMock, patch
@@ -274,6 +275,25 @@ class TestUpdateChecker:
         expected = "You are on the latest version: 2025+fb00f11 (compared to fb00f11 in channel latest)"
         assert any(expected in r.getMessage() for r in caplog.records)
 
+    def test_check_for_updates_respects_interval_gate(
+        self,
+        config:Config,
+        caplog:pytest.LogCaptureFixture
+    ) -> None:
+        """Ensure the interval guard short-circuits update checks without touching the network."""
+        caplog.set_level(logging.WARNING)
+
+        with patch.object(UpdateCheckState, "should_check", return_value = False) as should_check_mock, \
+                patch.object(UpdateCheckState, "update_last_check") as update_last_check_mock, \
+                patch("requests.get") as mock_get:
+            checker = UpdateChecker(config)
+            checker.check_for_updates()
+
+        should_check_mock.assert_called_once()
+        mock_get.assert_not_called()
+        update_last_check_mock.assert_not_called()
+        assert all("Could not determine local version" not in message for message in caplog.messages)
+
     def test_update_check_state_empty_file(self, state_file:Path) -> None:
         """Test that loading an empty state file returns a new state."""
         state_file.touch()  # Create empty file