fix(overton): update verdict — migration acceptance durable, non-migration temporary

Key finding from 2026 data:
- 2026-Q2 CS bounced back to 0.523 (from 0.334 in Q1)
- Migration CS (0.395) now EXCEEDS non-migration (0.368) for first time
- Multiple 2026-Q2 migration motions got unanimous centrist support (CS=1.00)

Updated verdict across synthesis, QMD, and HTML:
- Non-migration acceptance was a temporary electoral shock response
- Migration acceptance is durable and growing as debate intensifies
- The Overton shift is domain-specific, not uniformly temporary

Also fixed hashline formatting corruption in synthesis file.

reports/overton_window/overton_report.html

@@ -542,7 +542,7 @@
       <li><strong>Centrist tolerance increased at all gravity levels.</strong> Under both the all-party and strict 4-party centrist models, post-2024 centrist support was higher at gravity levels M3 through M5. The strict centrist core moved as well, not just the broader coalition.</li>
       <li><strong>Shift is not across the board &mdash; M5 motions remain largely rejected.</strong> Even after the window shift, motions at the highest gravity level (M5) received only 10.1% strict centrist support. Some positions remain firmly outside the Overton window regardless of the political climate.</li>
       <li><strong>Style and substance are only moderately correlated.</strong> With r = 0.43, the rhetorical framing of a motion and its substantive policy impact move partly independently. This means motions can be substantively radical but rhetorically cautious (like motion 144), potentially slipping through the window under the radar.</li>
-      <li><strong>Post-2025 downward trend suggests shift may be reversing.</strong> Strict centrist support for M3+ motions peaked in 2024 (0.487) and declined through 2025 (0.451) and 2026 (0.297). The 2026-Q1 reversion (CS = 0.334) shows material moderation persisted while stijl reverted. Critically, CS was already declining through 2025 despite continued policy moderation, suggesting the 2024 spike was primarily an electoral shock response rather than a sustained realignment.</li>
+      <li><strong>The shift is domain-specific: temporary for non-migration, durable for migration.</strong> Non-migration centrist support peaked in 2024 and declined through 2025-2026, suggesting an electoral shock response. However, 2026-Q2 shows CS bouncing back to 0.523, driven by the intensifying migration debate. For the first time, migration centrist support (0.395) exceeds non-migration (0.368) in 2026. Multiple 2026-Q2 migration motions received unanimous centrist support (CS = 1.00), including high-impact items. The Overton widening on migration appears self-sustaining.</li>
     </ul>
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