feat(tag-eval): inline confirm/reject actions on example thumbnails

Closes the learn-from-tags loop directly on the eval lists (operator-flagged:
no surface to confirm/refine the head's suggestions). Each thumbnail gets a
green ✓ / red ✗ that writes the SAME tables the head trains on:
- suggest + ✓  → apply tag (new positive, POST /images/<id>/tags)
- suggest + ✗  → record rejection (hard negative, suggestions/dismiss)
- doubt   + ✗  → remove tag + record rejection (kill bad positive, add negative)
- doubt   + ✓  → keep (stays a positive, no write)
Acted thumbs grey out with a badge; re-run to see the head sharpen. Thumb still
links to /explore/<id>. All endpoints already existed — no backend change.

Inline is the starting point; longer-term the modal Suggestions rail gets the
red "No" (negative) so per-image rejection is native there too (next slice).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/src/stores/tagEval.js

@@ -23,5 +23,29 @@ export const useTagEvalStore = defineStore('tagEval', () => {
     return (body.runs && body.runs[0]) || null
   }
 
-  return { start, getRun, latest }
+  // --- Acting on the head's example lists (closes the learn-from-tags loop).
+  // These write the SAME tables the head trains on: image_tag (positives) and
+  // tag_suggestion_rejection (negatives, via the dismiss endpoint).
+
+  // "Yes, it is this" — apply the tag (new positive).
+  async function applyTag(imageId, tagId) {
+    return await api.post(`/api/images/${imageId}/tags`,
+      { body: { tag_id: tagId, source: 'manual' } })
+  }
+
+  // "No, it's not" on an UNtagged suggestion — record a rejection (hard negative).
+  async function rejectTag(imageId, tagId) {
+    return await api.post(`/api/images/${imageId}/suggestions/dismiss`,
+      { body: { tag_id: tagId } })
+  }
+
+  // "Not it" on one of YOUR positives the head doubts — remove the tag AND
+  // record the rejection (kills the bad positive, leaves a hard negative).
+  async function removeTag(imageId, tagId) {
+    await api.delete(`/api/images/${imageId}/tags/${tagId}`)
+    return await api.post(`/api/images/${imageId}/suggestions/dismiss`,
+      { body: { tag_id: tagId } })
+  }
+
+  return { start, getRun, latest, applyTag, rejectTag, removeTag }
 })