fix(a11y): P3 — drop focus:outline-none on inputs; restore global :focus-visible

Phase 10a a11y audit (2026-04-29) flagged seven inputs across the app
that strip the global 2px :focus-visible outline (defined in app.css:251)
without providing a comparable replacement. Net effect: keyboard users
see at most a 1px border-colour shift on focus, sometimes nothing.

The fix removes the focus:outline-none override so the global rule
applies. Affected inputs:

- FilesPage: file-transcript textarea (F2).
- TasksPage: search input, quick-add input, inline list-edit, new-list
  input (T1, T2, T3, plus the new-list rename input).
- HistoryPage: top search, inline title rename, tag-add (H1).
- ImplementationRulesEditor: trigger/surface/task selects + speak-line
  input (S7).
- TaskSidebar, WipTaskList: quick-add inputs (S8).

The 1px focus:border-accent on inputs that had it is retained as a
secondary cue; the global 2px ring is now the primary indicator and
matches button focus across the app.

Resolves: F2, T1, T2, T3, H1, S7, S8.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/pages/TasksPage.svelte

@@ -377,7 +377,7 @@
       <Search size={14} class="text-text-tertiary flex-shrink-0" aria-hidden="true" />
       <input
         type="text"
-        class="flex-1 bg-transparent text-[12px] text-text placeholder:text-text-tertiary focus:outline-none"
+        class="flex-1 bg-transparent text-[12px] text-text placeholder:text-text-tertiary"
         placeholder="Search tasks..."
         bind:value={searchQuery}
         data-no-transition
@@ -395,7 +395,7 @@
       <Plus size={16} class="text-text-tertiary flex-shrink-0" aria-hidden="true" />
       <input
         type="text"
-        class="flex-1 bg-transparent text-[13px] text-text placeholder:text-text-tertiary focus:outline-none"
+        class="flex-1 bg-transparent text-[13px] text-text placeholder:text-text-tertiary"
         placeholder="Add a task to {activeListName}{activeBucket !== 'all' ? ` (${activeBucket})` : ''}... (Enter to save)"
         bind:value={quickInput}
         onkeydown={handleQuickAdd}
@@ -485,7 +485,7 @@
               <input
                 bind:this={editingInputEl}
                 type="text"
-                class="w-full bg-bg-input border border-accent rounded px-2 py-1 text-[10px] text-text focus:outline-none"
+                class="w-full bg-bg-input border border-accent rounded px-2 py-1 text-[10px] text-text"
                 bind:value={editingName}
                 onkeydown={(e) => { if (e.key === "Enter") finishRenaming(); if (e.key === "Escape") { editingListId = null; } }}
                 onblur={finishRenaming}
@@ -545,7 +545,7 @@
               bind:this={newListInputEl}
               type="text"
               class="w-full bg-bg-input border border-border rounded px-2 py-1 text-[10px] text-text
-                     placeholder:text-text-tertiary focus:outline-none focus:border-accent"
+                     placeholder:text-text-tertiary focus:border-accent"
               placeholder="List name..."
               bind:value={newListName}
               onkeydown={handleCreateList}