Rework the per-day location resolution so it can no longer fabricate weather for
days before the home was set. Precedence, first hit wins:
1. an explicit dated location period (a trip, or a corrected stretch of
history) covering the day;
2. DEVICE — a reserved slot for a future client-supplied coarse per-day
location (ranks between the period and home; not produced server-side yet);
3. the home location, but only for days on/after its effective-from date;
4. otherwise the day is skipped.
The home route stamps `homeSince` whenever the home is set/updated and returns
it. The overview exposes it. Backfill bounds are now optional and default to the
conservative `[homeSince .. today]` span instead of a fixed reach onto the
current home; days before `homeSince` still resolve to a skip in the worker, so
even a wider explicit start cannot back-fill weather for the pre-home past. To
reach further back a user adds an explicit location period for that range.
Add unit coverage for the precedence (including the effective-from boundary and
the skip-not-guess rule) and the default backfill range.
Add the opt-in Environment module (default off), its Settings surface (home
location search, travel overrides, backfill, with Open-Meteo attribution), the
gated API routes (overview, home, geocode, travel CRUD, backfill), the nightly
pg-boss fetch job with a lookback window plus on-demand backfill, the query
keys, six-locale strings, and the regenerated OpenAPI. The module performs an
outbound weather fetch tied to a coarse location, so it ships dark and the user
turns it on deliberately; off means no job, no row, no egress.
Marc-André Bombeck