Standardize API response envelope shapes across all endpoints

This commit standardizes how API responses are wrapped, solving issue #24.

Problem:
- Inconsistent response envelopes (jails vs items vs bans vs no wrapper)
- Frontend required multiple field name variants
- Integration bugs from branching logic
- No clear pattern for different response types

Solution:
- Created response.py with base classes: PaginatedListResponse,
  CollectionResponse, CommandResponse
- Standardized all list/collection responses to use 'items' field
- Domain-specific field names for detail and aggregation responses
- Updated all backends routers and mappers
- Updated frontend types and hooks to match

Changes:
Backend:
- backend/app/models/response.py (new): Base response models
- backend/app/models/ban.py: Updated responses to inherit from bases
- backend/app/models/jail.py: Updated JailListResponse, JailCommandResponse
- backend/app/models/config.py: Updated collection responses
- backend/app/services/jail_service.py: Updated return statements
- backend/app/mappers/ban_mappers.py: Updated 'bans' to 'items'
- backend/tests/test_mappers/test_ban_mappers.py: Updated tests

Frontend:
- frontend/src/types/jail.ts: Updated response interfaces
- frontend/src/types/config.ts: Updated response interfaces
- frontend/src/hooks/useActiveBans.ts: Updated selector
- frontend/src/hooks/useJailList.ts: Updated selector
- frontend/src/hooks/useJailConfigs.ts: Updated selector
- frontend/src/hooks/useConfigActiveStatus.ts: Updated field access
- frontend/src/hooks/useJailAdmin.ts: Updated field access

Documentation:
- Docs/Backend-Development.md: Added § 4.1 API Response Envelope Policy

The policy defines:
1. Paginated lists use PaginatedListResponse (items, total, page, page_size)
2. Non-paginated collections use CollectionResponse (items, total)
3. Detail responses use entity-specific field names (jail, status, settings)
4. Command responses use CommandResponse (message, success, optional target)
5. Aggregations use domain-specific fields (jails, countries, buckets, bans)

All responses now follow one of these patterns, reducing frontend complexity.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

backend/app/models/jail.py

@@ -6,6 +6,7 @@ Request, response, and domain models used by the jails router and service.
 from pydantic import BaseModel, ConfigDict, Field
 
 from app.models.config import BantimeEscalation
+from app.models.response import CommandResponse, CollectionResponse
 
 
 class JailStatus(BaseModel):
@@ -62,13 +63,13 @@ class JailSummary(BaseModel):
     status: JailStatus | None = None
 
 
-class JailListResponse(BaseModel):
-    """Response for ``GET /api/jails``."""
+class JailListResponse(CollectionResponse[JailSummary]):
+    """Response for ``GET /api/jails``.
 
-    model_config = ConfigDict(strict=True)
+    Returns a non-paginated collection of jail summaries with their current status.
+    """
 
-    jails: list[JailSummary] = Field(default_factory=list)
-    total: int = Field(..., ge=0)
+    pass
 
 
 class JailDetailResponse(BaseModel):
@@ -79,13 +80,13 @@ class JailDetailResponse(BaseModel):
     jail: Jail
 
 
-class JailCommandResponse(BaseModel):
-    """Generic response for jail control commands (start, stop, reload, idle)."""
+class JailCommandResponse(CommandResponse):
+    """Generic response for jail control commands (start, stop, reload, idle).
 
-    model_config = ConfigDict(strict=True)
+    Extends the base CommandResponse with a jail field to identify the target.
+    """
 
-    message: str
-    jail: str
+    jail: str = Field(..., description="Target jail name, or '*' for operations on all jails.")
 
 
 class IgnoreIpRequest(BaseModel):