fix(openapi): declare the body-cap 413 and the outbound-screen 502 of a briefing generation

Both have always been answered; neither was declared. The parity walk now
checks them against the contract instead of skipping it.

docs/api/openapi.yaml

@@ -12654,6 +12654,12 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/ErrorEnvelope"
+        "413":
+          description: The request body is over 16 KB. Nothing was generated.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorEnvelope"
         "422":
           description: No AI provider can serve the `briefing` capability (`meta.errorCode` = `ai.provider.none`, `meta.reason` =
             `no_provider`), or the provider answered something that was not valid JSON (`meta.errorCode` =
@@ -12672,6 +12678,13 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/ErrorEnvelope"
+        "502":
+          description: The generated briefing did not pass the outbound safety screen and was discarded (`meta.errorCode` =
+            `insights.generate.outboundScreened`). Regenerating may succeed.
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorEnvelope"
         "503":
           description: "Every provider in the chain failed for a reason that is not a rate limit — auth, timeout or an upstream
             5xx. A dated failure marker is written, so the read GET reports the briefing as held rather than fresh.