fix: increase login detection timeout to fix intermittent failures (#701) (#726)

## ℹ️ Description

This PR fixes intermittent login detection failures where the bot fails
to detect existing login sessions and unnecessarily re-logins,
potentially causing IP blocks.

- Link to the related issue(s): Issue #701
- Describe the motivation and context for this change:

Users reported that the bot sometimes fails to detect existing login
sessions (50/50 behavior), especially for browser profiles that haven't
been used for 20+ days. This appears to be a race condition where:
1. `web_open()` completes when `document.readyState == 'complete'`
2. But kleinanzeigen.de's client-side JavaScript hasn't yet rendered
user profile elements
3. The login detection timeout (5s default) is too short for slow
networks or sessions requiring server-side validation

## 📋 Changes Summary

- **Add dedicated `login_detection` timeout** to `TimeoutConfig`
(default: 10s, previously used generic 5s timeout)
- **Apply timeout to both DOM checks** in `is_logged_in()`: `.mr-medium`
and `#user-email` elements
- **Add debug logging** to track which element detected login or if no
login was found
- **Regenerate JSON schema** to include new timeout configuration
- **Effective total timeout**: ~22.5s (10s base × 1.0 multiplier × 1.5
backoff × 2 retries) vs previous ~11.25s

### Benefits:
- Addresses race condition between page load completion and client-side
rendering
- Provides sufficient time for sessions requiring server-side validation
(20+ days old)
- User-configurable via `timeouts.login_detection` in `config.yaml`
- Follows established pattern of dedicated timeouts (`sms_verification`,
`gdpr_prompt`, etc.)

### ⚙️ 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

* **New Features**
* Added a configurable login-detection timeout (default 10s, min 1s) to
tune session detection.

* **Bug Fixes**
* More reliable login checks using a timeout-aware, two-step detection
sequence.
* Improved diagnostic logging for login attempts, retry behavior,
detection outcomes, and timeout events.

* **Documentation**
* Added troubleshooting guidance explaining the login-detection timeout
and when to adjust it.

<sub>✏️ Tip: You can customize this high-level summary in your review
settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

README.md

@@ -292,6 +292,7 @@ timeouts:
   captcha_detection: 2.0              # Timeout for captcha iframe detection
   sms_verification: 4.0               # Timeout for SMS verification banners
   gdpr_prompt: 10.0                   # Timeout when handling GDPR dialogs
+  login_detection: 10.0               # Timeout for detecting existing login session via DOM elements
   publishing_result: 300.0            # Timeout for publishing status checks
   publishing_confirmation: 20.0       # Timeout for publish confirmation redirect
   image_upload: 30.0                  # Timeout for image upload and server-side processing