Give each e2e test its own reliable peer

The page always talked to the shared palm backend, so tests couldn't set
up peers of their own. Peers now have no passphrase by default, so tests
don't need an ssh-agent and test keys stay out of the developer's agent.
Fixtures wait for replication instead of relying on gossip timing, and a
request cancelled by a reload no longer counts as a page error.

.github/workflows/e2e.yaml

@@ -28,7 +28,8 @@ jobs:
             libayatana-appindicator3-dev \
             librsvg2-dev \
             libwebkit2gtk-4.1-dev \
-            libjavascriptcoregtk-4.1-dev
+            libjavascriptcoregtk-4.1-dev \
+            openssh-client
       - run: npm ci
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2