ci: fix E2E postgres-test collision and smoke @playwright/test resolution

E2E: test-server.mjs always spins up its own postgres-test container
and publishes port 5432 on the docker host — colliding with Gitea's
core postgres on the QNAP runner. Add PLAYWRIGHT_USE_EXTERNAL_DB
opt-in so CI can reuse the e2epg job-service container (which
test-server still pushes+seeds into). Set the flag in the E2E job.

docker-deploy smoke: install @playwright/test locally (no -g, no
--save) so the CJS require() in apps/web/playwright.ci.config.ts
resolves it by walking up from the config directory. Global npm
install lands in a hostedtoolcache path Node does not search.

apps/web/e2e/test-server.mjs

@@ -334,9 +334,18 @@ if (!playwrightDatabaseUrl) {
   throw new Error("PLAYWRIGHT_DATABASE_URL or DATABASE_URL_TEST must be configured for E2E runs.");
 }
 
-const requestedTestDbPort = Number(new URL(playwrightDatabaseUrl).port || "5434");
-const selectedTestDbPort = await selectAvailablePort(requestedTestDbPort);
-playwrightDatabaseUrl = replaceDatabasePort(playwrightDatabaseUrl, selectedTestDbPort);
+// CI mode: use an externally-provided postgres (e.g. a GitHub Actions service
+// container) instead of spinning up our own compose-managed postgres-test.
+// In that mode we trust PLAYWRIGHT_DATABASE_URL as-is — no port rebinding,
+// no compose up.
+const useExternalDb = process.env.PLAYWRIGHT_USE_EXTERNAL_DB === "true";
+
+let selectedTestDbPort;
+if (!useExternalDb) {
+  const requestedTestDbPort = Number(new URL(playwrightDatabaseUrl).port || "5434");
+  selectedTestDbPort = await selectAvailablePort(requestedTestDbPort);
+  playwrightDatabaseUrl = replaceDatabasePort(playwrightDatabaseUrl, selectedTestDbPort);
+}
 
 const playwrightDatabaseName = parseDatabaseName(playwrightDatabaseUrl);
 
@@ -348,7 +357,9 @@ if (!/(^|_)(test|e2e|ci)$/u.test(playwrightDatabaseName)) {
 
 process.env.DATABASE_URL = playwrightDatabaseUrl;
 process.env.PLAYWRIGHT_DATABASE_URL = playwrightDatabaseUrl;
-process.env.POSTGRES_TEST_PORT = String(selectedTestDbPort);
+if (selectedTestDbPort !== undefined) {
+  process.env.POSTGRES_TEST_PORT = String(selectedTestDbPort);
+}
 process.env.CAPAKRAKEN_EXPECTED_DB_NAME = playwrightDatabaseName;
 process.env.ALLOW_DESTRUCTIVE_DB_TOOLS = "true";
 process.env.CONFIRM_DESTRUCTIVE_DB_NAME = playwrightDatabaseName;
@@ -378,8 +389,10 @@ writeManagedWebEnv(rootEnv);
 process.on("exit", restoreWebEnvOnce);
 
 try {
-  await cleanupStaleE2eArtifacts();
-  await ensureE2eDatabaseContainer();
+  if (!useExternalDb) {
+    await cleanupStaleE2eArtifacts();
+    await ensureE2eDatabaseContainer();
+  }
   await run("pnpm", ["--filter", "@capakraken/db", "db:push"], workspaceRoot);
   await run("pnpm", ["--filter", "@capakraken/db", "db:seed"], workspaceRoot);
   await run("pnpm", ["--filter", "@capakraken/db", "db:seed:holidays"], workspaceRoot);