Add proactive financial intelligence feed

Shifts the AI assistant from reactive (users ask questions) to proactive
(the system surfaces personalized insights automatically). A nightly job
analyzes every family's financial data across 7 insight types, writes
natural-language explanations via Claude, and surfaces them in a feed on
the dashboard and a standalone /insights page.

Feature is behind a flag: off by default, enable with INSIGHTS_ENABLED=1
(or via Setting.insights_enabled in the admin UI).

Insight types:
- spending_anomaly: category spend >25% above/below 3-month rolling average
- cash_flow_warning: projected cash balance drops below $500 in 30 days
  (uses RecurringTransaction + statistical daily baseline)
- net_worth_milestone: crossed a round-number milestone or all-time high
- subscription_audit: recurring transaction overdue by 45+ days
- savings_rate_change: savings rate changed >5 percentage points vs last month
- idle_cash: $5k+ sitting in depository account with no activity in 60 days
- budget_at_risk / budget_on_track: spending pace vs monthly budget

Architecture:
- Insight model with dedup_key unique index (upsert, not re-create daily)
- Insight::Generator base class + Insight::GeneratorRegistry orchestrator
- LLM used as a writer only — financial math runs in pure Ruby
- GenerateInsightsJob runs at 6 AM UTC daily via sidekiq-cron
- InsightsController with read/dismiss Turbo Stream actions
- Dashboard section gated by Current.user.insights_enabled?

https://claude.ai/code/session_014vY9xohpm3abSAxVxRF27a

app/controllers/insights_controller.rb

@@ -0,0 +1,39 @@
+class InsightsController < ApplicationController
+  include FeatureGuardable
+
+  guard_feature unless: -> { Current.user.insights_enabled? }
+
+  before_action :set_insight, only: %i[read dismiss]
+
+  def index
+    @insights = Current.family.insights
+                  .visible
+                  .ordered
+  end
+
+  def read
+    @insight.mark_read!
+    respond_to do |format|
+      format.turbo_stream { render turbo_stream: turbo_stream.replace(@insight, partial: "insights/insight_card", locals: { insight: @insight, compact: false }) }
+      format.html { redirect_to insights_path }
+    end
+  end
+
+  def dismiss
+    @insight.dismiss!
+    respond_to do |format|
+      format.turbo_stream { render turbo_stream: turbo_stream.remove(@insight) }
+      format.html { redirect_to insights_path }
+    end
+  end
+
+  def refresh
+    GenerateInsightsJob.perform_later(family_id: Current.family.id)
+    redirect_to insights_path, notice: t("insights.refresh_queued")
+  end
+
+  private
+    def set_insight
+      @insight = Current.family.insights.find(params[:id])
+    end
+end

app/controllers/pages_controller.rb

@@ -84,7 +84,17 @@ class PagesController < ApplicationController
     end
 
     def build_dashboard_sections
+      insights = Current.user.insights_enabled? ? Current.family.insights.for_dashboard.to_a : []
+
       all_sections = [
+        {
+          key:         "insights_feed",
+          title:       "pages.dashboard.insights_feed.title",
+          partial:     "pages/dashboard/insights_feed",
+          locals:      { insights: insights },
+          visible:     Current.user.insights_enabled? && insights.any?,
+          collapsible: true
+        },
         {
           key: "cashflow_sankey",
           title: "pages.dashboard.cashflow_sankey.title",