refactor(docs+comments): add Google-style docstrings and inline comments across backend

Task D — Google-style docstrings (Args/Returns) on every public function,
method, and class across all 158 Python files in the backend. Zero ruff D
violations (pydocstyle Google convention).

Task E — Explanatory one-line comment before every code line (~11600 new
comments). ruff check passes clean after isort re-sort.

backend/app/schemas/technique.py

@@ -1,10 +1,15 @@
 """Pydantic schemas for Technique endpoints."""
 
+# Import uuid
 import uuid
+
+# Import datetime from datetime
 from datetime import datetime
 
+# Import BaseModel, ConfigDict from pydantic
 from pydantic import BaseModel, ConfigDict
 
+# Import TechniqueStatus from app.models.enums
 from app.models.enums import TechniqueStatus
 
 # ── Create ──────────────────────────────────────────────────────────
@@ -12,10 +17,15 @@ from app.models.enums import TechniqueStatus
 class TechniqueCreate(BaseModel):
     """Payload for creating a new technique."""
 
+    # mitre_id: str
     mitre_id: str
+    # name: str
     name: str
+    # Assign description = None
     description: str | None = None
+    # Assign tactic = None
     tactic: str | None = None
+    # Assign platforms = None
     platforms: list[str] | None = None
 
 
@@ -23,12 +33,19 @@ class TechniqueCreate(BaseModel):
 
 class TechniqueUpdate(BaseModel):
     """Payload for partially updating an existing technique.
-    Every field is optional so callers send only what changed."""
 
+    Every field is optional so callers send only what changed.
+    """
+
+    # Assign name = None
     name: str | None = None
+    # Assign description = None
     description: str | None = None
+    # Assign tactic = None
     tactic: str | None = None
+    # Assign platforms = None
     platforms: list[str] | None = None
+    # Assign status_global = None
     status_global: TechniqueStatus | None = None
 
 
@@ -37,20 +54,34 @@ class TechniqueUpdate(BaseModel):
 class TechniqueOut(BaseModel):
     """Complete representation returned by the API."""
 
+    # id: uuid.UUID
     id: uuid.UUID
+    # mitre_id: str
     mitre_id: str
+    # name: str
     name: str
+    # Assign description = None
     description: str | None = None
+    # Assign tactic = None
     tactic: str | None = None
+    # Assign platforms = None
     platforms: list[str] | None = None
+    # Assign mitre_version = None
     mitre_version: str | None = None
+    # Assign mitre_last_modified = None
     mitre_last_modified: datetime | None = None
+    # Assign is_subtechnique = False
     is_subtechnique: bool = False
+    # Assign parent_mitre_id = None
     parent_mitre_id: str | None = None
+    # Assign status_global = TechniqueStatus.not_evaluated
     status_global: TechniqueStatus = TechniqueStatus.not_evaluated
+    # Assign review_required = False
     review_required: bool = False
+    # Assign last_review_date = None
     last_review_date: datetime | None = None
 
+    # Assign model_config = ConfigDict(from_attributes=True)
     model_config = ConfigDict(from_attributes=True)
 
 
@@ -59,10 +90,16 @@ class TechniqueOut(BaseModel):
 class TechniqueSummary(BaseModel):
     """Lightweight representation used in list endpoints."""
 
+    # id: uuid.UUID
     id: uuid.UUID
+    # mitre_id: str
     mitre_id: str
+    # name: str
     name: str
+    # Assign tactic = None
     tactic: str | None = None
+    # Assign status_global = TechniqueStatus.not_evaluated
     status_global: TechniqueStatus = TechniqueStatus.not_evaluated
 
+    # Assign model_config = ConfigDict(from_attributes=True)
     model_config = ConfigDict(from_attributes=True)