Add keyboard shortcuts system with reusable hint components

- Implement centralized keyboard registry with 20+ shortcuts
- Add instance navigation (Cmd+[1-9], Cmd+[/])
- Add session navigation (Cmd+Shift+[1-9], Cmd+Shift+[/])
- Add agent/model cycling (Tab, Cmd+Shift+M)
- Add input shortcuts (Cmd+P focus, Cmd+K clear, ↑↓ history)
- Add command palette (Cmd+Shift+P) with 8 MVP commands
- Implement message history per folder in IndexedDB (max 100)
- Create reusable Kbd and HintRow components
- Replace all keyboard hint rendering with consistent components
- Use text-based shortcuts (Cmd+Shift+M) for clarity

src/stores/command-palette.ts

@@ -0,0 +1,17 @@
+import { createSignal } from "solid-js"
+
+const [isOpen, setIsOpen] = createSignal(false)
+
+export function showCommandPalette() {
+  setIsOpen(true)
+}
+
+export function hideCommandPalette() {
+  setIsOpen(false)
+}
+
+export function toggleCommandPalette() {
+  setIsOpen(!isOpen())
+}
+
+export { isOpen }

src/stores/message-history.ts

@@ -0,0 +1,51 @@
+import { saveHistory, loadHistory, deleteHistory } from "../lib/db"
+
+const MAX_HISTORY = 100
+
+const instanceHistories = new Map<string, string[]>()
+const historyLoaded = new Set<string>()
+
+export async function addToHistory(instanceId: string, text: string): Promise<void> {
+  await ensureHistoryLoaded(instanceId)
+
+  const history = instanceHistories.get(instanceId) || []
+
+  history.unshift(text)
+
+  if (history.length > MAX_HISTORY) {
+    history.length = MAX_HISTORY
+  }
+
+  instanceHistories.set(instanceId, history)
+
+  saveHistory(instanceId, history).catch((err) => {
+    console.warn("Failed to persist message history:", err)
+  })
+}
+
+export async function getHistory(instanceId: string): Promise<string[]> {
+  await ensureHistoryLoaded(instanceId)
+  return instanceHistories.get(instanceId) || []
+}
+
+export async function clearHistory(instanceId: string): Promise<void> {
+  instanceHistories.delete(instanceId)
+  historyLoaded.delete(instanceId)
+  await deleteHistory(instanceId)
+}
+
+async function ensureHistoryLoaded(instanceId: string): Promise<void> {
+  if (historyLoaded.has(instanceId)) {
+    return
+  }
+
+  try {
+    const history = await loadHistory(instanceId)
+    instanceHistories.set(instanceId, history)
+    historyLoaded.add(instanceId)
+  } catch (error) {
+    console.warn("Failed to load history:", error)
+    instanceHistories.set(instanceId, [])
+    historyLoaded.add(instanceId)
+  }
+}