Pin the itest piri image to the last sqlite-compatible digest

piri:main now requires Postgres for its curio PDP pipeline, but smelt
boots piri with the sqlite/filesystem config, so the itest stack fails
during piri startup and every suite dies waiting on it. Pin the piri
image (via the existing INGOT_ITEST_PIRI_IMAGE escape hatch) to the
digest smelt's 3-piri-filesystem-sqlite snapshot was built against
until the stack and image agree again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015WqgCRxsD9tzd7L2m5mMLW

Author: claude

.github/workflows/go-test.yml

@@ -55,6 +55,13 @@ jobs:
         # working-tree binary itself (itest/stack_test.go).
         env:
           GOWORK: off
+          # TEMPORARY pin: piri:main moved past smelt's sqlite/filesystem
+          # config (its curio PDP pipeline now refuses to boot without
+          # Postgres — "curio PDP pipeline requires Postgres"), so the stack
+          # never comes up. This is the digest smelt's own snapshot was built
+          # against (snapshots/3-piri-filesystem-sqlite). Drop the pin once
+          # smelt configures piri's database or piri restores the sqlite path.
+          INGOT_ITEST_PIRI_IMAGE: ghcr.io/fil-forge/piri@sha256:31509ada4fb33418b650907dcae96d7178cf6c35b5161cf6a73e2bffe51aca9e
         run: go test -tags itest -v -timeout 20m ./itest
 
       - name: Dump container state on failure