fix: hide section-locked filter pills in their own sections

Each section's preset locks one filter dimension that defines the
section: Rated → ratingMin, Discarded → flag, Tags → groupBy=tag.
Showing the matching pill in the toolbar while you're inside that
section is either redundant (it's already on) or actively breaks the
view (toggling it would either become a no-op or filter the section
into one bucket).

Hide the corresponding pill in each section: Rating in Rated, Flag in
Discarded, Tags in Tags. The user navigates away to a different
section to change the locked dimension.

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

frontend/src/components/filter/FilterBar.tsx

@@ -45,6 +45,16 @@ export function FilterBar() {
   const sortBy = useFilterStore((s) => s.sortBy)
   const sortOrder = useFilterStore((s) => s.sortOrder)
   const tagIds = useFilterStore((s) => s.tagIds)
+  const currentSection = useFilterStore((s) => s.currentSection)
+
+  // Section-locked pills: each section has a preset filter that defines
+  // it (Rated → ratingMin, Discarded → flag, Tags → groupBy=tag). The
+  // matching pill is hidden while you're inside that section because
+  // toggling it would either be a no-op or break the section. The user
+  // can still navigate away to change the locked dimension.
+  const hideRatingPill = currentSection === 'rated'
+  const hideFlagPill = currentSection === 'discarded'
+  const hideTagsPill = currentSection === 'tags'
 
   const setDateFrom = useFilterStore((s) => s.setDateFrom)
   const setDateTo = useFilterStore((s) => s.setDateTo)
@@ -216,7 +226,10 @@ export function FilterBar() {
         </div>
       </FilterPill>
 
-      {/* Rating */}
+      {/* Rating — hidden in the Rated section since the section already
+       *  pins ratingMin and the only useful tweak (ratingMin >= N) lives
+       *  in the section preset itself. */}
+      {!hideRatingPill && (
         <FilterPill
           label="Rating"
           value={ratingValue}
@@ -246,6 +259,7 @@ export function FilterBar() {
             </div>
           </div>
         </FilterPill>
+      )}
 
       {/* Color */}
       <FilterPill
@@ -282,7 +296,9 @@ export function FilterBar() {
         </div>
       </FilterPill>
 
-      {/* Flag — discarded toggle */}
+      {/* Flag — hidden in the Discarded section, where the flag is
+       *  pinned to "discarded" by the section preset. */}
+      {!hideFlagPill && (
         <FilterPill
           label="Flag"
           value={flagValue}
@@ -314,9 +330,12 @@ export function FilterBar() {
             </button>
           </div>
         </FilterPill>
+      )}
 
-      {/* Tags */}
+      {/* Tags — hidden in the Tags section since the section already
-      {allTags.length > 0 && (
+       *  groups everything by tag and re-applying a tag filter on top
+       *  collapses the view to a single bucket. */}
+      {!hideTagsPill && allTags.length > 0 && (
         <FilterPill
           label="Tags"
           value={tagValue}