Take portal v0.5.1

Attachments both ways, rate limiting, sessions that survive a deploy,
and an upload route that asks the policy like every other way in.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitea/workflows/lint-and-reload.yml

@@ -20,7 +20,7 @@ jobs:
       # this site runs (PORTAL_RELEASE in deploy.yml).
       - name: Lint questions
         env:
-          IRIS_RELEASE: v0.4.0
+          IRIS_RELEASE: v0.5.1
         run: |
           # The checkout is on a noexec mount for this runner; the cargo
           # target dir is where it may run what it fetched.