refactor(semantics): migrate TIER system to adaptive COMPLEXITY 1-5 scale

- Replaced rigid TIERs with continuous COMPLEXITY 1-5 scale in semantics.md
- Updated generate_semantic_map.py to parse and score based on Complexity
- Added backward compatibility mapping for legacy TIERs
- Migrated all .ai/shots examples to use @COMPLEXITY and updated relation syntax
- Added trivial_utility.py shot to demonstrate implicit Complexity 1 token savings

.ai/shots/backend_route.py

@@ -1,10 +1,9 @@
 #[DEF:BackendRouteShot:Module]
-# @TIER: STANDARD
+# @COMPLEXITY: 3
 # @SEMANTICS: Route, Task, API, Async
 # @PURPOSE: Reference implementation of a task-based route using GRACE-Poly.
 # @LAYER: Interface (API)
-# @RELATION: IMPLEMENTS -> [DEF:Std:API_FastAPI]
-# @INVARIANT: TaskManager must be available in dependency graph.
+# @RELATION: [IMPLEMENTS] ->[API_FastAPI]
 
 from typing import Dict, Any
 from fastapi import APIRouter, Depends, HTTPException, status
@@ -25,15 +24,13 @@ class CreateTaskRequest(BaseModel):
 # [/DEF:CreateTaskRequest:Class]
 
 # [DEF:create_task:Function]
+# @COMPLEXITY: 4
 # @PURPOSE: Create and start a new task using TaskManager. Non-blocking.
-# @DATA_CONTRACT: Input -> CreateTaskRequest, Output -> Task
+# @RELATION: [CALLS] ->[task_manager.create_task]
 # @PRE: plugin_id must match a registered plugin.
 # @POST: A new task is spawned; Task object returned immediately.
 # @SIDE_EFFECT: Writes to DB, Triggers background worker.
-#
-# @UX_STATE: Success -> 201 Created
-# @UX_STATE: Error(Validation) -> 400 Bad Request
-# @UX_STATE: Error(System) -> 500 Internal Server Error
+# @DATA_CONTRACT: Input -> CreateTaskRequest, Output -> Task
 @router.post("/tasks", response_model=Task, status_code=status.HTTP_201_CREATED)
 async def create_task(
     request: CreateTaskRequest,