fix(api): accept Pireon webhooks from the password client too

Pireon signs each webhook with the secret of the client that registered
it, and the API has two clients (the web app's and the password
grant's). Only PIREON_WEBHOOK_SECRET was accepted, so a token revoked
for someone signed in with a password went unheard. A delivery now
verifies with PIREON_WEBHOOK_SECRET or PIREON_PASSWORD_WEBHOOK_SECRET;
the same event arriving from both clients changes nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/openapi.json

@@ -344,7 +344,7 @@
     },
     "/api/webhooks/pireon": {
       "post": {
-        "description": "`user.deactivated` closes the user's sessions; `token.revoked` forgets the token. Disabled unless PIREON_WEBHOOK_SECRET is set.",
+        "description": "`user.deactivated` closes the user's sessions; `token.revoked` forgets the token. Disabled unless PIREON_WEBHOOK_SECRET or PIREON_PASSWORD_WEBHOOK_SECRET is set.",
         "operationId": "PireonWebhookController_receive",
         "parameters": [
           {
@@ -358,7 +358,7 @@
           {
             "name": "X-Webhook-Signature",
             "in": "header",
-            "description": "HMAC-SHA256 of the raw body with PIREON_WEBHOOK_SECRET (hex)",
+            "description": "HMAC-SHA256 of the raw body with the secret of the Pireon client that registered the webhook (hex)",
             "required": true,
             "schema": {
               "type": "string"