Initial commit: PRD, build tooling, and design mockups

Foodster is a self-hosted dinner log and meal suggester for one household.
Stage 1 (eating history) is in development; stage 2 (the suggester) follows
once there is enough history to weight against.

Replace the PRD's original stack (Nuxt, Postgres, Drizzle, Pico CSS) with
Go 1.27, net/http, templ, Datastar and SQLite — one static binary, no
Node.js in the build. Sections 3, 4, 5, 9, 10 and 11 are rewritten to match.

Record the decisions made while reviewing mockups:

- the UI is written in Finnish; PRD, code and comments stay English
- access is one shared password over HTTP Basic rather than open on the LAN
- images are CalVer vYYYYMMDD-N, built with Podman, run under Docker Compose
- registry coordinates live in .env, so no infrastructure detail is
  committed and the MIT publication option stays open

mockups/ holds standalone HTML design studies. log-fi.html is the current
one; the others are superseded exploration kept for reference.

.env.example

@@ -0,0 +1,17 @@
+# Copy to .env and fill in. .env is gitignored — the real registry hostname
+# must not end up in the repository.
+
+# Image coordinates. FOODSTER_REPO carries no tag.
+FOODSTER_REPO=registry.example.com/you/foodster
+FOODSTER_TAG=latest
+
+# Shared household password. The app will not start without it.
+FOODSTER_PASSWORD=changeme
+
+# Host port to publish on.
+FOODSTER_PORT=8080
+
+# Used for every calendar-day calculation. Set it in development too: under
+# UTC the date rolls over three hours late, which is exactly when dinner
+# gets logged.
+TZ=Europe/Helsinki