chore: sync docs with single-page app, fix jsconfig

- docs: drop stale /master route refs (system-architecture page flow,
  client-only file list, basePath profiles; pdr architecture section
  + acceptance items; codebase-summary mounted-on notes; code-standards
  link example; deployment-guide redirect explanation)
- roadmap: drop "Currently Implemented Features" section (lives in git
  log + plans + pdr/codebase-summary)
- jsconfig: extend .svelte-kit/tsconfig.json (clears SvelteKit warning,
  picks up generated paths/aliases)

web/jsconfig.json

@@ -1,14 +1,7 @@
 {
+  "extends": "./.svelte-kit/tsconfig.json",
   "compilerOptions": {
-    "module": "esnext",
-    "moduleResolution": "bundler",
-    "target": "es2022",
     "allowJs": true,
-    "checkJs": false,
-    "paths": {
-      "$lib": ["./src/lib"],
-      "$lib/*": ["./src/lib/*"]
-    }
-  },
-  "include": ["src/**/*", "vite.config.js", "svelte.config.js"]
+    "checkJs": false
+  }
 }