feat: view and edit a transaction's note from the list

Transactions can carry a `notes` field (set via the API — e.g. the
currency-conversion metadata on this user's imported historical data), but
there was no way to see it in the UI at all.

TransactionsTable now shows a note icon next to edit/delete, only when a
transaction actually has one, opening a dialog with the text. The edit
form's `notes` field was already wired end to end (state, payload) but had
no input in the JSX — added it, since a view-only note with no way to edit
or clear it would be a dead end.

Also fixed e2e/run.sh's readiness check, found while running the full
suite for this change: it polled `/` (nginx, answers almost immediately)
instead of `/api/health`, so the first test could start before the backend
finished migrating/seeding and fail trying to parse nginx's HTML error
page as JSON.

e2e/run.sh

@@ -23,9 +23,13 @@ trap cleanup EXIT
 
 $COMPOSE up -d --build
 
-echo "waiting for http://localhost:${AURUM_WEB_PORT} ..."
+echo "waiting for http://localhost:${AURUM_WEB_PORT}/api/health ..."
+# /api/health, not just / — nginx (the `web` container) answers the bare root
+# well before the backend has finished running migrations + seeding, and a
+# request racing ahead of that gets nginx's own HTML error page back instead
+# of JSON, which the first test to touch the API then fails to parse.
 for _ in $(seq 1 60); do
-  if curl -sf "http://localhost:${AURUM_WEB_PORT}" >/dev/null; then
+  if curl -sf "http://localhost:${AURUM_WEB_PORT}/api/health" >/dev/null; then
     echo "stack is up"
     break
   fi