Rewrite in Go with templ, HTMX and sqlc on Postgres

[malpou]

Replaces the SvelteKit/Cloudflare/D1 stack with Go. Behaviour is unchanged, and
that isn't a claim: all seven Playwright spec files pass byte-for-byte
untouched, which is what pinned nearly every decision in here.

git diff main -- 'e2e/*.spec.ts'   # empty

The stack

• Go + templ render the HTML.
• HTMX owns everything that talks to the server. Forms keep naming their
  action in the query string (?/addOption), and hx-post intercepts the
  submit so a rejected form re-renders in place without changing the URL.
• Alpine owns the in-page state that never needed a round-trip: the
  preference selector, the submit gate, the inline edit and expand toggles.
• sqlc compiles internal/db/queries.sql into typed Go over pgx/v5,
  generated into internal/db beside store.go, so the store uses the
  generated row types directly and there is no mapping layer.
• Tailwind 4 builds to a static static/app.css.

Worth a look in review

Dates. The Go stdlib ships no CLDR data, so internal/domain/date.go spells
out the weekday/month names and the per-locale date and time shapes. Two traps
worth knowing about, both pinned in date_test.go: Danish writes the time with
a dot (kl. 10.00) where en/fr use a colon (at 10:00), and the same UTC
instant renders 10.00 in September but 09.00 in January.

Hidden vs absent. Collapsed notes and respondent names use x-if, not
x-show. Two dashboard specs assert toHaveCount(0) on collapsed content, which
only holds if it is absent from the DOM rather than merely hidden - and a
collapsed card genuinely shouldn't ship who answered to the client.

One source of truth for copy. messages/{da,en,fr}.json is read by the Go
server to render and by the specs to assert, so copy cannot drift between the app
and the tests. That is the only reason src/lib/paraglide still exists: the
specs import it by that path.

Generated code is committed and marked in .gitattributes, so a fresh clone
builds and tests without templ/sqlc/tailwind installed. CI runs make build and
fails if the tree is dirty afterwards, so it can't rot.

The harness (the only thing touched outside the app)

The specs are untouched; their harness is not. e2e/db.ts keeps its exact
exported API but seeds through psql instead of wrangler. global-setup.ts is
gone: Playwright waits for webServer to be ready before it would run any
global setup, so a database started there is too late for the server that needs
it. The database now comes up with the server via compose.yaml.

Deploy note

This is no longer a Worker. It's a single Go binary plus static/, needing
DATABASE_URL and optionally PORT, so poll.malpou.io needs somewhere that
can run it. Apply internal/db/migrations/0001_init.sql to a fresh database
before first boot.