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one; the others are superseded exploration kept for reference.

compose.yaml

@@ -0,0 +1,15 @@
+services:
+  app:
+    image: ${FOODSTER_REPO:?set FOODSTER_REPO in .env}:${FOODSTER_TAG:-latest}
+    restart: unless-stopped
+    ports:
+      - "${FOODSTER_PORT:-8080}:8080"
+    environment:
+      FOODSTER_PASSWORD: ${FOODSTER_PASSWORD:?set FOODSTER_PASSWORD in .env}
+      FOODSTER_DB: /data/foodster.db
+      TZ: ${TZ:-Europe/Helsinki}
+    volumes:
+      - foodster-data:/data
+
+volumes:
+  foodster-data: