feat(app): add Electron desktop UI and evolve memory/retrieval layer

Introduce an Electron app with session browser, memory list, and usage
  views (vanilla JS + Vue scaffolding). On the data layer: add content_type
  and is_meta to messages for transcript control-plane filtering, introduce
  FTS5-backed memory recall with safe tokenization, support memory archival
  via forget() through the renamed --attune runtime, and expose anchors on
  memory records.

app/preload.js

@@ -0,0 +1,22 @@
+const { contextBridge, ipcRenderer } = require('electron');
+
+contextBridge.exposeInMainWorld('obelisk', {
+  getSessions: (opts) => ipcRenderer.invoke('db:getSessions', opts),
+  getSessionMessages: (id) => ipcRenderer.invoke('db:getSessionMessages', id),
+  getSessionToolCalls: (id) => ipcRenderer.invoke('db:getSessionToolCalls', id),
+  getSessionToolResults: (id) => ipcRenderer.invoke('db:getSessionToolResults', id),
+  getSessionSubagents: (id) => ipcRenderer.invoke('db:getSessionSubagents', id),
+  getSessionWorkflows: (id) => ipcRenderer.invoke('db:getSessionWorkflows', id),
+  getSubagentMessages: (agentId) => ipcRenderer.invoke('db:getSubagentMessages', agentId),
+  getSubagentToolCalls: (agentId) => ipcRenderer.invoke('db:getSubagentToolCalls', agentId),
+  getSubagentToolResults: (agentId) => ipcRenderer.invoke('db:getSubagentToolResults', agentId),
+  getSessionSummaries: (id) => ipcRenderer.invoke('db:getSessionSummaries', id),
+  getMessageFullText: (uuid) => ipcRenderer.invoke('db:getMessageFullText', uuid),
+  getMemories: () => ipcRenderer.invoke('db:getMemories'),
+  readMemoryFile: (path) => ipcRenderer.invoke('db:readMemoryFile', path),
+  archiveMemory: (id, reason) => ipcRenderer.invoke('db:archiveMemory', id, reason),
+  restoreMemory: (id) => ipcRenderer.invoke('db:restoreMemory', id),
+  getProjects: () => ipcRenderer.invoke('db:getProjects'),
+  getStats: () => ipcRenderer.invoke('db:getStats'),
+  getUsageStats: () => ipcRenderer.invoke('db:getUsageStats'),
+});