feat!: require explicit user on every tenant-data endpoint

Remove the implicit jpmschweitzer default tenant (DEFAULT_USER) from
src/core/multi_tenancy.py and every endpoint and request model that
inherited it (~40 endpoints across /query, /wiki, /vector, /graph,
/ingest, /volatile, /documents, /stats, /rag).

- Add validate_required_user() + RequiredUser pydantic type in
  multi_tenancy and a shared require_user FastAPI dependency
  (RequiredUserQuery) that rejects missing, empty, and whitespace-only
  users with 422, following the /maintenance/* pattern.
- Wiki page create / smart-create / dossier request models now require
  user (no fallback in wiki_service).
- /maintenance/cleanup/test-data derives the tenant from the page path
  instead of using the production tenant collection.
- Wiki.js change listener skips changes when no tenant user can be
  derived from the notification email instead of defaulting to the
  production tenant.
- Consolidation service internal helpers no longer default to the
  production tenant.
- Tool catalog marks user as required with honest descriptions.
- OpenAPI descriptions updated honestly; CHANGELOG notes that callers
  (tatlock, Scheduler ingest tasks) must now send explicit user.
- Offline tests: 422 coverage for query/body endpoints, required-user
  validator tests; updated legacy tests that assumed a default tenant.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/models/vector.py

@@ -7,6 +7,8 @@ Provides models for semantic search, document chunks, and embeddings.
 from pydantic import BaseModel, Field
 from typing import List, Dict, Any, Optional
 
+from src.core.multi_tenancy import RequiredUser
+
 
 class DocumentChunk(BaseModel):
     """Document chunk with embedding."""
@@ -32,7 +34,7 @@ class SearchResult(BaseModel):
 class SearchRequest(BaseModel):
     """Semantic search request."""
     query: str = Field(..., min_length=1, description="Search query")
-    user: str = Field(default="jpmschweitzer", description="User identifier")
+    user: RequiredUser = Field(..., description="User identifier (tenant). Required — search is scoped to this tenant's collection.")
     limit: int = Field(default=10, ge=1, le=100, description="Maximum results")
     score_threshold: float = Field(default=0.5, ge=0.0, le=1.0, description="Minimum similarity score")
 
@@ -48,9 +50,9 @@ class SearchResponse(BaseModel):
 class VectorUpdateRequest(BaseModel):
     """Request to update vectors from a wiki page."""
     page_id: int = Field(..., description="Wiki page ID to process")
-    user: str = Field(
-        default="jpmschweitzer",
-        description="User identifier for namespace scoping"
+    user: RequiredUser = Field(
+        ...,
+        description="User identifier (tenant). Required — vectors are written to this tenant's collection."
     )
     force_refresh: bool = Field(
         default=False,
@@ -89,7 +91,7 @@ class CollectionListResponse(BaseModel):
 class DeletePageChunksRequest(BaseModel):
     """Request to delete all chunks for a page."""
     page_id: int = Field(..., description="Wiki page ID")
-    user: str = Field(default="jpmschweitzer", description="User identifier")
+    user: RequiredUser = Field(..., description="User identifier (tenant). Required — deletion is scoped to this tenant's collection.")
 
 
 class DeletePageChunksResponse(BaseModel):