ci: build workspaces before running tests; set PUBLIC_URL=https://logicsrc.com

The 'test' workflow ran 'npm test' without building, so dependents could not
resolve @logicsrc/plugin-core / @logicsrc/validators (they publish from dist/).
Build first. Also document PUBLIC_URL (canonical site URL) in .env.example.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.env.example

@@ -1,3 +1,5 @@
+# Canonical public site URL (used for CoinPay redirect/webhook URLs and secure cookies)
+PUBLIC_URL=https://logicsrc.com
 COMMANDBOARD_API_URL=http://localhost:4010
 COMMANDBOARD_TOKEN=
 COMMANDBOARD_DID=

.github/workflows/test.yml

@@ -22,6 +22,10 @@ jobs:
 
       - run: npm ci
 
+      # Workspace packages (e.g. @logicsrc/plugin-core, @logicsrc/validators)
+      # publish from dist/, so dependents can't resolve them until built.
+      - run: npm run build
+
       - run: npm test
         env:
           CI: true