fix: JSON API Pagination for >25 Ads (#797)

## ℹ️ Description
*Provide a concise summary of the changes introduced in this pull
request.*

- Link to the related issue(s): Closes #789 (completes the fix started
in #793)
- **Motivation**: Fix JSON API pagination for accounts with >25 ads.
Aligns pagination logic with weidi’s approach (starts at page 1), while
hardening error handling and tests. Based on
https://github.com/weidi/kleinanzeigen-bot/pull/1.

## 📋 Changes Summary

- Added pagination helper to fetch all published ads and use it in
delete/extend/publish/update flows
- Added robust handling for malformed JSON payloads and unexpected ads
types (with translated warnings)
- Improved sell_directly extraction with pagination, bounds checks, and
shared coercion helper
- Added/updated tests for pagination and edge cases; updated assertions
to pytest.fail style

### ⚙️ Type of Change
Select the type(s) of change(s) included in this pull request:
- [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
Before requesting a review, confirm the following:
- [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:cov:unified`).
- [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**
* Reliable multi-page fetching for published ads and buy-now eligibility
checks.

* **Bug Fixes**
* Safer pagination with per-page JSON handling, limits and improved
termination diagnostics; ensures pageNum is used when needed.

* **Tests**
* New comprehensive pagination tests and updates to existing tests to
reflect multi-page behavior.

* **Chores**
* Added a utility to safely coerce page numbers; minor utility signature
cleanup.

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

src/kleinanzeigen_bot/extract.py

@@ -25,6 +25,7 @@ __all__ = [
 LOG:Final[loggers.Logger] = loggers.get_logger(__name__)
 
 _BREADCRUMB_MIN_DEPTH:Final[int] = 2
+_SELL_DIRECTLY_MAX_PAGE_LIMIT:Final[int] = 100
 BREADCRUMB_RE = re.compile(r"/c(\d+)")
 
 
@@ -525,19 +526,56 @@ class AdExtractor(WebScrapingMixin):
                 LOG.warning("Could not extract ad ID from URL: %s", self.page.url)
                 return None
 
-            # Fetch the management JSON data using web_request
-            response = await self.web_request("https://www.kleinanzeigen.de/m-meine-anzeigen-verwalten.json")
-            json_data = json.loads(response["content"])
+            # Fetch the management JSON data using web_request with pagination support
+            page = 1
 
-            # Find the current ad in the ads list
-            if isinstance(json_data, dict) and "ads" in json_data:
-                ads_list = json_data["ads"]
-                if isinstance(ads_list, list):
-                    # Filter ads to find the current ad by ID
-                    current_ad = next((ad for ad in ads_list if ad.get("id") == current_ad_id), None)
-                    if current_ad and "buyNowEligible" in current_ad:
-                        buy_now_eligible = current_ad["buyNowEligible"]
-                        return buy_now_eligible if isinstance(buy_now_eligible, bool) else None
+            while True:
+                # Safety check: don't paginate beyond reasonable limit
+                if page > _SELL_DIRECTLY_MAX_PAGE_LIMIT:
+                    LOG.warning("Stopping pagination after %s pages to avoid infinite loop", _SELL_DIRECTLY_MAX_PAGE_LIMIT)
+                    break
+
+                response = await self.web_request(f"https://www.kleinanzeigen.de/m-meine-anzeigen-verwalten.json?sort=DEFAULT&pageNum={page}")
+
+                try:
+                    json_data = json.loads(response["content"])
+                except json.JSONDecodeError as ex:
+                    LOG.debug("Failed to parse JSON response on page %s: %s", page, ex)
+                    break
+
+                # Find the current ad in the ads list
+                if isinstance(json_data, dict) and "ads" in json_data:
+                    ads_list = json_data["ads"]
+                    if isinstance(ads_list, list):
+                        # Filter ads to find the current ad by ID
+                        current_ad = next((ad for ad in ads_list if ad.get("id") == current_ad_id), None)
+                        if current_ad and "buyNowEligible" in current_ad:
+                            buy_now_eligible = current_ad["buyNowEligible"]
+                            return buy_now_eligible if isinstance(buy_now_eligible, bool) else None
+
+                # Check if we need to fetch more pages
+                paging = json_data.get("paging") if isinstance(json_data, dict) else None
+                if not isinstance(paging, dict):
+                    break
+
+                # Parse pagination info using real API fields
+                current_page_num = misc.coerce_page_number(paging.get("pageNum"))
+                total_pages = misc.coerce_page_number(paging.get("last"))
+
+                if current_page_num is None:
+                    LOG.warning("Invalid 'pageNum' in paging info: %s, stopping pagination", paging.get("pageNum"))
+                    break
+
+                # Stop if we've reached the last page
+                if total_pages is None or current_page_num >= total_pages:
+                    break
+
+                # Use API's next field for navigation (more robust than our counter)
+                next_page = misc.coerce_page_number(paging.get("next"))
+                if next_page is None:
+                    LOG.warning("Invalid 'next' page value in paging info: %s, stopping pagination", paging.get("next"))
+                    break
+                page = next_page
 
             # If the key doesn't exist or ad not found, return None (unknown)
             return None