feat(client,setting): complete Phase 2 with partitioned client_follow_logs

- apps/client (11 models): Client, ClientContact, ClientRequirement,
  ClientSchoolPreference, ClientFollowLog (partitioned),
  ClientFollowLogAttachment, ClientViewing, ClientPropertyMatch,
  ClientStatusLog, ClientFavoriteFolder, ClientFolderItem
- apps/client/0002 RunSQL: PARTITION BY RANGE(created_at) for
  client_follow_logs + monthly partitions + default; triggers
  update_client_last_follow + update_client_viewing_progress;
  partial unique index on client_no WHERE deleted_at IS NULL
- apps/setting (4 models): LookupGroup, LookupItem, TenantSetting,
  FieldRequirementRule (tenant schema only per spec)

manage.py check green; all 9 Phase 2 apps complete.

apps/setting/models/setting.py

@@ -0,0 +1,75 @@
+from django.db import models
+
+from core.enums import (
+    FieldRuleEntityType,
+    FieldRuleModule,
+    FieldRuleRequirement,
+    SettingValueType,
+)
+from core.models.base import UUIDPrimaryKeyModel
+
+TRADE_STATUS_CHOICES = (
+    ("sale", "出售"),
+    ("rent", "出租"),
+    ("sale_rent", "租售"),
+    ("*", "全部"),
+)
+
+
+class TenantSetting(UUIDPrimaryKeyModel):
+    category = models.CharField(max_length=50)
+    key = models.CharField(max_length=100)
+    value = models.JSONField()
+    value_type = models.CharField(max_length=20, choices=SettingValueType.choices)
+    updated_by = models.ForeignKey(
+        "org.Staff",
+        null=True,
+        blank=True,
+        on_delete=models.SET_NULL,
+        related_name="updated_tenant_settings",
+    )
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        db_table = "tenant_settings"
+        constraints = [
+            models.UniqueConstraint(
+                fields=["category", "key"], name="uq_tenant_settings_cat_key"
+            ),
+        ]
+        indexes = [
+            models.Index(fields=["category"], name="idx_tenant_settings_cat"),
+        ]
+
+
+class FieldRequirementRule(UUIDPrimaryKeyModel):
+    module = models.CharField(max_length=20, choices=FieldRuleModule.choices)
+    entity_type = models.CharField(max_length=50, choices=FieldRuleEntityType.choices)
+    trade_status = models.CharField(max_length=20, choices=TRADE_STATUS_CHOICES)
+    field_key = models.CharField(max_length=50)
+    requirement = models.CharField(
+        max_length=10, choices=FieldRuleRequirement.choices
+    )
+    updated_by = models.ForeignKey(
+        "org.Staff",
+        null=True,
+        blank=True,
+        on_delete=models.SET_NULL,
+        related_name="updated_field_rules",
+    )
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        db_table = "field_requirement_rules"
+        constraints = [
+            models.UniqueConstraint(
+                fields=["module", "entity_type", "trade_status", "field_key"],
+                name="uq_field_req_quad",
+            ),
+        ]
+        indexes = [
+            models.Index(
+                fields=["module", "entity_type", "trade_status"],
+                name="idx_field_req_lookup",
+            ),
+        ]