feat(ui): one-click 'Hide off-topic' toggle on the Trump feed

Lets the user collapse every post the AI judged off-topic (not crypto-related,
never scored) so the feed shows only real signals.

- PostCards exports isAiScored(post) as the single source of truth for what
  counts as noise — the card de-emphasis and the list filter now share it, so
  they can never disagree.
- TrumpPageClient: 'Hide off-topic (N)' toggle in the filter row (only shown
  when N>0), with live noise count. Resets to page 1 on toggle.

tsc + build clean.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/dashboard/PostCards.tsx

@@ -3,6 +3,16 @@
 import { memo, useEffect, useState } from 'react'
 import type { TrumpPost } from '@/types'
 
+/**
+ * Was this post actually AI-scored, or filtered as off-topic noise before any
+ * AI call? Single source of truth — used both by the card (to de-emphasise
+ * noise) and by list views (to offer a "collapse off-topic" toggle), so the
+ * two can never disagree about what counts as noise.
+ */
+export function isAiScored(post: Pick<TrumpPost, 'ai_confidence' | 'ai_reasoning'>): boolean {
+  return (post.ai_confidence ?? 0) > 0 || !!post.ai_reasoning
+}
+
 function fmtPct(n: number | null | undefined) {
   if (n == null || isNaN(n)) return '—'   // null = window not yet closed
   const s = n.toFixed(2) + '%'
@@ -102,14 +112,10 @@ const PostRow = memo(function PostRow({ post, selected, onClick }: PostRowProps)
     onClick?.()
   }
 
-  // Did this post actually get an AI score, or was it filtered as off-topic
-  // noise before any AI call? Trump posts mostly aren't crypto-related, so the
-  // entry filter / AI marks them relevant=false with confidence 0 and no
-  // reasoning. Showing "AI confidence 0%" + an empty bar for those is
-  // misleading — it reads as "AI looked and had zero confidence" when really
-  // "this was skipped as not crypto-relevant". Treat a post as AI-scored only
-  // when it has a real confidence or reasoning.
-  const aiScored = post.ai_confidence > 0 || !!post.ai_reasoning
+  // Off-topic Trump posts (most of them) are filtered before any AI call, so
+  // they carry confidence 0 + no reasoning. Treat those as un-scored noise and
+  // de-emphasise them. Shared helper so list-level "collapse off-topic" agrees.
+  const aiScored = isAiScored(post)
 
   return (
     <div