ci: stop building on every push — extension ships via Web Store

The CI/CD Pipeline and Quality Gates workflows were running full
builds (npm ci, tests, typecheck, lint, audit, coverage, perf) on
every push to main, even though the extension is published manually
to the Chrome Web Store — none of these gate a release.

Result: every README tweak generated 3 red X's for drift in a frozen
dep stack (Biome 1.9, TS 5.9, @types/chrome 0.0.254) that will be
addressed in a dedicated modernization pass.

- ci.yml: push + PR triggers → workflow_dispatch + release only
- quality-gates.yml: push trigger → workflow_dispatch + PR only

security.yml keeps its daily cron — that one still earns its place
by catching new CVEs on the frozen deps.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Wolfe-Jam

.github/workflows/ci.yml

@@ -1,10 +1,7 @@
 name: 🚀 CI/CD Pipeline
 
 on:
-  push:
-    branches: [main, develop]
-  pull_request:
-    branches: [main, develop]
+  workflow_dispatch:
   release:
     types: [published]
 

.github/workflows/quality-gates.yml

@@ -1,10 +1,9 @@
 name: 🚪 Quality Gates
 
 on:
+  workflow_dispatch:
   pull_request:
     branches: [main]
-  push:
-    branches: [main]
 
 env:
   NODE_VERSION: 18.x