feat: add community contribution ranks

apps/gamification/models.py

@@ -0,0 +1,53 @@
+import uuid
+
+from django.conf import settings
+from django.db import models
+from django.db.models import Q
+
+
+class ContributionLedger(models.Model):
+    class Activity(models.TextChoices):
+        ATTENDANCE = "attendance", "Event attendance"
+        POST = "post", "Published post"
+        COMMENT = "comment", "Approved comment or reply"
+        LIKE = "like", "Like given or received"
+        SAVE = "save", "Save given or received"
+
+    user = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        related_name="contribution_ledger_entries",
+    )
+    activity = models.CharField(max_length=20, choices=Activity.choices)
+    source_type = models.CharField(max_length=32)
+    source_id = models.CharField(max_length=80)
+    effect_key = models.CharField(max_length=240, db_index=True)
+    role = models.CharField(max_length=20)
+    points = models.IntegerField()
+    idempotency_key = models.UUIDField(default=uuid.uuid4, unique=True, editable=False)
+    reversal_of = models.ForeignKey(
+        "self",
+        null=True,
+        blank=True,
+        on_delete=models.PROTECT,
+        related_name="reversals",
+    )
+    reason = models.CharField(max_length=120, blank=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        ordering = ["created_at", "id"]
+        indexes = [
+            models.Index(fields=["user", "activity"]),
+            models.Index(fields=["source_type", "source_id"]),
+        ]
+        constraints = [
+            models.CheckConstraint(condition=~Q(points=0), name="gamification_nonzero_ledger_points"),
+        ]
+
+
+class ScoringEpoch(models.Model):
+    """The launch boundary for blog scoring; historical blog rows remain unscored."""
+
+    id = models.PositiveSmallIntegerField(primary_key=True, default=1, editable=False)
+    started_at = models.DateTimeField()