feat: property reputation from visitors, resistant to farming

Property worlds now give their property reputation for the time other people spend on it, which
fills the property lists and the news screen's Today's Top Properties. Visitors are counted per
account; the owner's account, accounts linked to it and staff don't count. A visit earns nothing
for the first property_reputation_min_visit seconds (WorldConfig's propertyReputationDelay), then
each active minute (the visitor moved) earns reputationPerMinute times a multiplier, for a capped
number of minutes per visit. Repeat visitors earn less the more recent days they already gave
reputation, and each visitor and each property have a daily cap. Every parameter is a setting;
what each account gave each property per day is kept in property_reputation_visits. The rules are
pure functions with unit tests.

Fixes #636
Fixes #637

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/Dashboard.md

@@ -899,6 +899,36 @@ property is made private. It can't be made public or best friends only again unt
 told in chat when they try), and a property world that loads with overdue rent makes itself private too. Nothing on
 the property changes. The property's page shows the rent last charged and when the next is due.
 
+### Property reputation
+
+Properties earn reputation from visitors; it orders the in-game property lists and the news screen's **Today's Top
+Properties**, and the showcase. Live first gave 1 point per minute a visitor spent on a property (each
+PropertyTemplate's `reputationPerMinute` is 1) and later replaced that with an unpublished algorithm because it was
+easy to farm. The client only displays the number the server sends, so the server decides. This one keeps "time
+other people spend on the property" as the signal and makes farming it expensive (settings under Gameplay, Property
+reputation; the code is `dCommon/PropertyReputationRules.h`):
+
+1. **Only other people.** Visitors are counted per account, so the owner's characters never count and one account
+   with several characters on the property is one visitor. Accounts linked to the owner's (same play key, email or
+   login address, as on the Linked accounts panel; `property_reputation_ignore_linked`) and staff
+   (`property_reputation_ignore_staff`) don't count either.
+2. **A minimum visit.** Nothing for the first `property_reputation_min_visit` seconds (120, WorldConfig's
+   `propertyReputationDelay`), so hopping in and out does nothing.
+3. **Active minutes.** Once a minute, a visitor who moved at least 2 units since the last minute
+   (`property_reputation_require_activity`) earns `reputationPerMinute` × `property_reputation_multiplier` points,
+   for at most `property_reputation_max_minutes` (30) minutes per visit. An idle alt parked on a property earns nothing.
+4. **Diminishing returns for regulars.** A visitor who gave the property reputation on *d* of the last
+   `property_reputation_repeat_days` (30) days earns 1 / (1 + `property_reputation_repeat_falloff` × *d*) as much
+   (0.5: half on the third day, a fifth after eight). Fractions carry over between the minutes of a visit.
+5. **Daily caps** (UTC days): one account gives one property at most `property_reputation_visitor_daily_cap` (30)
+   points a day, and a property gets at most `property_reputation_daily_cap` (300) a day from everyone.
+
+With the defaults a stranger spending 20 active minutes gives 19 points; the same account coming back every day for a
+week gives about 100 in total, less than seven different visitors staying 20 minutes each. Small servers can raise the
+multiplier. Nothing decays. What each account gave each property per day is kept in `property_reputation_visits`
+(`GET /api/properties/:id/reputation` sums the last 30 days); the character's own reputation (from missions) is not
+changed.
+
 ### Properties in 3D
 
 **Open 3D view** on a property page (or *View in 3D* next to a model) shows every placed model on the zone's terrain,