feat(desktop): persistent needs-input indicator + icon button consolidation

Replace the background-clarify toast (expired on alt-tab, easy to miss) with a
persistent, glowing amber "needs input" dot on the session's sidebar row,
driven off a new ClientSessionState.needsInput flag mirrored into a
$attentionSessionIds store. The flag is set on clarify.request and cleared the
moment the turn resumes (tool.complete) or ends.

Also: redesign the clarify tool UI (borderless choices, pseudo-radio dots,
right-aligned checkmark, arc border, tighter padding), make Button the single
source of icon-button styling (4px radius, new icon-titlebar variant, titlebar
buttons rendered polymorphically via asChild, Codicons throughout), put the
file-tree refresh action first, and .trim() pasted composer text.

apps/desktop/src/store/session.test.ts

@@ -2,7 +2,7 @@ import { describe, expect, it } from 'vitest'
 
 import type { SessionInfo } from '@/types/hermes'
 
-import { mergeSessionPage, sessionPinId } from './session'
+import { $attentionSessionIds, mergeSessionPage, sessionPinId, setSessionAttention } from './session'
 
 const session = (over: Partial<SessionInfo>): SessionInfo => ({
   archived: false,
@@ -23,6 +23,34 @@ const session = (over: Partial<SessionInfo>): SessionInfo => ({
   ...over
 })
 
+describe('setSessionAttention', () => {
+  it('adds and removes a session id without duplicating it', () => {
+    $attentionSessionIds.set([])
+
+    setSessionAttention('s1', true)
+    setSessionAttention('s1', true)
+    expect($attentionSessionIds.get()).toEqual(['s1'])
+
+    setSessionAttention('s2', true)
+    expect($attentionSessionIds.get()).toEqual(['s1', 's2'])
+
+    setSessionAttention('s1', false)
+    expect($attentionSessionIds.get()).toEqual(['s2'])
+
+    $attentionSessionIds.set([])
+  })
+
+  it('ignores empty ids and no-op clears', () => {
+    $attentionSessionIds.set([])
+
+    setSessionAttention(null, true)
+    setSessionAttention(undefined, true)
+    setSessionAttention('', true)
+    setSessionAttention('missing', false)
+    expect($attentionSessionIds.get()).toEqual([])
+  })
+})
+
 describe('sessionPinId', () => {
   it('uses the live id when there is no compression lineage', () => {
     expect(sessionPinId(session({ id: 'abc' }))).toBe('abc')