analytics: consolidate everything onto one shared Plausible pa- script

All pcbjam properties now load the same new-format Plausible script
(https://plausible.io/js/pa-KjNS9YmidydULZTstsjRg.js — one dashboard,
segment by hostname) instead of per-domain data-domain sites:

- site: replace Vercel Analytics with the pa- snippet in BaseLayout
  (is:inline, prod-only, crossorigin="anonymous" for the COEP
  require-corp routes in vercel.json); drop @vercel/analytics dep.
  Legal pages (cookies/privacy) rewritten Vercel -> Plausible.
- standalone: initAnalytics() rewritten for the new script format
  (queue shim + plausible.init(), async, no data-domain). The gate is
  now VITE_PLAUSIBLE_SRC (script URL, deploy-time opt-in) — unset means
  no tracking, so dev checkouts and third-party GPL builds stay clean.
  VITE_PLAUSIBLE_DOMAIN is gone.
- deploy: build-demo/build-editor --plausible now takes the script URL;
  release.yml/deploy-demo.yml hardcode the (public) pa- URL, so the
  repo Actions variable PLAUSIBLE_DOMAIN is no longer used.

Verified: standalone tsc + vite build (pa- URL present with env, absent
without, crossOrigin kept); astro build has the snippet on all layout
pages and no vercel/insights references; astro dev stays untracked.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

site/package-lock.json

@@ -11,7 +11,6 @@
         "@astrojs/mdx": "^6.0.3",
         "@astrojs/vercel": "^10.0.8",
         "@fontsource/oswald": "^5.2.8",
-        "@vercel/analytics": "^2.0.1",
         "astro": "^6.4.4",
         "resend": "^6.12.4"
       },
@@ -2304,48 +2303,6 @@
       "integrity": "sha512-mUFwbeTqrVgDQxFveS+df2yfap6iuP20NAKAsBt5jDEoOTDew+zwLAOilHCeQJOVSvmgCX4ogqIrA0mnyr08yQ==",
       "license": "ISC"
     },
-    "node_modules/@vercel/analytics": {
-      "version": "2.0.1",
-      "resolved": "https://registry.npmjs.org/@vercel/analytics/-/analytics-2.0.1.tgz",
-      "integrity": "sha512-MTQG6V9qQrt1tsDeF+2Uoo5aPjqbVPys1xvnIftXSJYG2SrwXRHnqEvVoYID7BTruDz4lCd2Z7rM1BdkUehk2g==",
-      "license": "MIT",
-      "peerDependencies": {
-        "@remix-run/react": "^2",
-        "@sveltejs/kit": "^1 || ^2",
-        "next": ">= 13",
-        "nuxt": ">= 3",
-        "react": "^18 || ^19 || ^19.0.0-rc",
-        "svelte": ">= 4",
-        "vue": "^3",
-        "vue-router": "^4"
-      },
-      "peerDependenciesMeta": {
-        "@remix-run/react": {
-          "optional": true
-        },
-        "@sveltejs/kit": {
-          "optional": true
-        },
-        "next": {
-          "optional": true
-        },
-        "nuxt": {
-          "optional": true
-        },
-        "react": {
-          "optional": true
-        },
-        "svelte": {
-          "optional": true
-        },
-        "vue": {
-          "optional": true
-        },
-        "vue-router": {
-          "optional": true
-        }
-      }
-    },
     "node_modules/@vercel/cli-config": {
       "version": "0.2.0",
       "resolved": "https://registry.npmjs.org/@vercel/cli-config/-/cli-config-0.2.0.tgz",
@@ -4327,6 +4284,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4347,6 +4305,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4367,6 +4326,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4387,6 +4347,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4407,6 +4368,7 @@
       "cpu": [
         "arm"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4427,6 +4389,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4447,6 +4410,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4467,6 +4431,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4487,6 +4452,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4507,6 +4473,7 @@
       "cpu": [
         "arm64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -4527,6 +4494,7 @@
       "cpu": [
         "x64"
       ],
+      "dev": true,
       "license": "MPL-2.0",
       "optional": true,
       "os": [