[AZ-365] Refactor C12: decompose RouteService.CreateRouteAsync

Extract RouteValidator (aggregating validator), RoutePointGraphBuilder
(point interpolation + sequence numbering), GeofenceGridCalculator
(NW/SE region centers), and RouteResponseMapper (entity -> DTO; also
used by GetRouteAsync, eliminating duplicate DTO assembly).

CreateRouteAsync shrinks 184 -> 52 LOC of orchestration. RouteService.cs
shrinks 295 -> 138 LOC overall. Validation aggregates all failures into
a single ArgumentException (AC-2); single-violation messages preserved
verbatim so existing RouteServiceTests pass unchanged. 28 new unit
tests for the four helpers (112/112 unit tests, smoke green).

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/02_tasks/todo/AZ-365_refactor_decompose_route_create_method.md

@@ -1,71 +0,0 @@
-# Refactor: decompose RouteService.CreateRouteAsync 165-LOC method
-
-**Task**: AZ-365_refactor_decompose_route_create_method
-**Name**: Split CreateRouteAsync into validator + builder + grid + mapper
-**Description**: Extract `RouteValidator`, `RoutePointGraphBuilder`, `GeofenceGridCalculator`, and `RouteResponseMapper` from `RouteService.CreateRouteAsync`.
-**Complexity**: 5 points
-**Dependencies**: None
-**Component**: Services.RouteManagement
-**Tracker**: AZ-365
-**Epic**: AZ-350
-
-## Problem
-
-`SatelliteProvider.Services.RouteManagement/RouteService.cs:27-211` is a 165-LOC method that does input validation (4 separate rules, ~25 LOC of nested `if` chains), point-graph construction with `GeoUtils.CalculateIntermediatePoints`, route entity persistence, route-points persistence, geofence polygon validation, geofence grid generation, geofence region requests, and response mapping. Five distinct responsibilities in one method.
-
-## Outcome
-
-- `CreateRouteAsync` is reduced to orchestration of the four extracted helpers (~30-50 LOC).
-- Validation aggregates errors instead of short-circuiting on the first.
-- Each helper is unit-testable in isolation.
-- 37 unit + 5 smoke tests stay green.
-
-## Scope
-
-### Included
-- Extract `RouteValidator` (all `ArgumentException`-throwing checks; aggregates errors instead of short-circuiting).
-- Extract `RoutePointGraphBuilder` (interpolation + sequence numbering — pure).
-- Extract `GeofenceGridCalculator` (NW/SE → list of region centers — promote the existing private method).
-- Extract `RouteResponseMapper` (entity → DTO; eliminates duplication with `GetRouteAsync`).
-- Add unit tests for each helper.
-
-### Excluded
-- Changing the response shape.
-- Changing the persistence calls.
-- Changing the geofence semantics.
-
-## Acceptance Criteria
-
-**AC-1: CreateRouteAsync is now an orchestrator**
-Given the post-refactor source
-When `CreateRouteAsync` is inspected
-Then it is reduced to ~30-50 LOC of `_validator.Validate(...)`, `_pointGraphBuilder.Build(...)`, `_geofenceGridCalculator.GenerateRegions(...)`, `_responseMapper.Map(...)` calls (or equivalent).
-
-**AC-2: Validation aggregates errors**
-Given an input with multiple validation failures
-When validated
-Then all failures are collected and surfaced as a single 400 response (still typed as `ArgumentException` or a typed `ValidationException`).
-
-**AC-3: Same persistence + same response**
-Given any input that succeeds today
-When the post-refactor code runs
-Then the same DB rows are created and the same response shape is returned.
-
-**AC-4: Tests stay green**
-Given the post-refactor build
-When `scripts/run-tests.sh --smoke` runs
-Then all 37 unit + 5 smoke scenarios pass; `RouteServiceTests` is unchanged.
-
-## Constraints
-
-- Same persistence calls.
-- Same response shape (no DTO change).
-- 400 status preserved for validation failures.
-
-## Risks & Mitigation
-
-**Risk 1: aggregated validation surfaces multiple errors but tests assert on first**
-- *Risk*: existing tests may assert on a specific single-error message.
-- *Mitigation*: update test assertions to allow a list of errors.
-
-Full change entry: `_docs/04_refactoring/03-code-quality-refactoring/list-of-changes.md` (C12).