refactor: replace array-based expressions with typed class hierarchy

Replace the old Lisp-like array expression representation
(["AND", ["PARAM", ...], ...]) with a class hierarchy rooted in
an abstract Expression class (Literal, Parameter, Binary, Unary,
FunctionCall, Conditional). This gives compile-time type safety
to expression construction, evaluation, and pattern matching.

Key changes:
- New lib/common/expression.ts defines the class hierarchy with
  map/evaluate/toString methods
- Rewrite parser as hand-rolled recursive descent, removing the
  parsimmon dependency
- Extend Path with a colon separator to unify parameter identity
  and attributes into a single address space (e.g.
  "Device.WiFi.SSID.1.Name:writable"). The colon field tracks
  how many trailing segments are attribute qualifiers. PathSet
  rewritten with separate param/attr segment indexes
- Flatten device attribute representation in the UI to
  colon-delimited keys mirroring the new path syntax

ui/app.ts

@@ -20,19 +20,37 @@ import { contextifyComponent } from "./components.ts";
 import { PermissionSet, UiConfig } from "../lib/types.ts";
 import drawerComponent from "./drawer-component.ts";
 import { render as renderOverlay } from "./overlay.ts";
+import Expression from "../lib/common/expression.ts";
 
 declare global {
   interface Window {
     authorizer: Authorizer;
-    permissionSets: PermissionSet[];
+    permissionSets: {
+      [resource: string]: { access: number; validate: string; filter: string };
+    }[][];
     username: string;
-    clientConfig: { ui: UiConfig };
+    clientConfig: UiConfig;
     configSnapshot: string;
     genieacsVersion: string;
   }
 }
 
-window.authorizer = new Authorizer(window.permissionSets);
+const permissionSets: PermissionSet[] = window.permissionSets.map((p) =>
+  p.map((s) =>
+    Object.fromEntries(
+      Object.entries(s).map(([resource, { access, validate, filter }]) => [
+        resource,
+        {
+          access,
+          validate: Expression.parse(validate),
+          filter: Expression.parse(filter),
+        },
+      ]),
+    ),
+  ),
+);
+
+window.authorizer = new Authorizer(permissionSets);
 
 let state;