feat: structured user profile with LLM-learned preferences

Replaces the freeform briefing-profile note with a DB-backed user_profiles
table. Users can edit job/industry/expertise/response preferences/interests/
work schedule via a new Settings → Profile tab. The LLM appends nightly
observations; at 14+ entries they are auto-consolidated into a learned_summary.
Profile context is injected into both briefing and chat system prompts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/client.ts

@@ -667,3 +667,26 @@ export async function synthesiseSpeech(
   }
   return res.blob()
 }
+
+// ── User Profile ─────────────────────────────────────────────────────────────
+
+export interface UserProfile {
+  display_name: string
+  job_title: string
+  industry: string
+  expertise_level: 'novice' | 'intermediate' | 'expert'
+  response_style: 'concise' | 'balanced' | 'detailed'
+  tone: 'casual' | 'professional' | 'technical'
+  interests: string[]
+  work_schedule: { days?: string[]; start?: string; end?: string }
+  learned_summary: string
+  observations_count: number
+  observations_updated_at: string | null
+}
+
+export const getProfile = () => apiGet<UserProfile>('/api/profile')
+export const updateProfile = (data: Partial<UserProfile>) =>
+  apiPut<UserProfile>('/api/profile', data)
+export const consolidateProfile = () =>
+  apiPost<{ status: string; learned_summary: string }>('/api/profile/consolidate', {})
+export const clearProfileObservations = () => apiDelete('/api/profile/observations')