fix(consent): add Sourcepoint iframe handler + banner_detector fallback

Root cause: Spiegel DSI text was truncated because Sourcepoint consent
wall was not dismissed — dsi_helpers.py had no Sourcepoint handler.

Fixes:
1. Add Sourcepoint iframe click (frame_locator + .sp_choice_type_11)
2. Add banner_detector fallback (reuses 30 CMP selectors from scanner)
3. After banner dismiss, wait and re-navigate if page redirected
4. Add "Zustimmen und weiter" to generic text button list

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

consent-tester/services/dsi_discovery.py

@@ -249,7 +249,17 @@ async def discover_dsi_documents(
         # Step 1b: Try dismissing cookie consent banners before extraction.
         # Many German sites (dm.de, Zalando, etc.) block page content behind
         # a consent wall. Dismissing it reveals the actual DSI text.
-        await try_dismiss_consent_banner(page)
+        banner_dismissed = await try_dismiss_consent_banner(page)
+        if banner_dismissed:
+            # After consent, page may reload or reveal hidden content
+            await page.wait_for_timeout(2000)
+            # Re-navigate if the page redirected after consent
+            try:
+                if page.url != url:
+                    await goto_resilient(page, url, timeout=30000)
+                    await page.wait_for_timeout(2000)
+            except Exception:
+                pass
 
         # Step 1c: Self-extraction — if the URL itself is a DSI page,
         # extract its full text as the first document. This handles the