Add privacy mode with blur toggle for financial data

- Stimulus controller on global layout (persists across all pages)
- CSS blur effect on .privacy-sensitive elements (8px active, 4px on hover)
- localStorage persistence survives page navigations
- Toggle button on dashboard with aria-pressed for accessibility
- Applied to 28+ views: accounts, budgets, transactions, reports, etc.

Fixes: UTF-8 encoding, global controller mount, aria-pressed attribute

app/javascript/controllers/privacy_mode_controller.js

@@ -0,0 +1,32 @@
+import { Controller } from "@hotwired/stimulus"
+
+// Privacy Mode Controller
+// Toggles visibility of financial numbers across the page.
+// Elements with class "privacy-sensitive" will be blurred when active.
+// State persists in localStorage so it survives page navigations.
+export default class extends Controller {
+  static targets = ["toggle"]
+
+  connect() {
+    this.active = localStorage.getItem("privacyMode") === "true"
+    this._apply()
+  }
+
+  toggle() {
+    this.active = !this.active
+    localStorage.setItem("privacyMode", this.active.toString())
+    this._apply()
+  }
+
+  _apply() {
+    if (this.active) {
+      document.documentElement.classList.add("privacy-mode")
+    } else {
+      document.documentElement.classList.remove("privacy-mode")
+    }
+
+    this.toggleTargets.forEach((el) => {
+      el.setAttribute("aria-pressed", this.active.toString())
+    })
+  }
+}