Onboarding: template backlink, bulk-create endpoint, climate-region scoring

Clients that send users through a multi-task onboarding step no longer
loop N POST /api/tasks/ calls and no longer create "orphan" tasks with
no reference to the TaskTemplate they came from.

Task model
- New task_template_id column + GORM FK (migration 000016)
- CreateTaskRequest.template_id, TaskResponse.template_id
- task_service.CreateTask persists the backlink

Bulk endpoint
- POST /api/tasks/bulk/ — 1-50 tasks in a single transaction,
  returns every created row + TotalSummary. Single residence access
  check, per-entry residence_id is overridden with batch value
- task_handler.BulkCreateTasks + task_service.BulkCreateTasks using
  db.Transaction; task_repo.CreateTx + FindByIDTx helpers

Climate-region scoring
- templateConditions gains ClimateRegionID; suggestion_service scores
  residence.PostalCode -> ZipToState -> GetClimateRegionIDByState against
  the template's conditions JSON (no penalty on mismatch / unknown ZIP)
- regionMatchBonus 0.35, totalProfileFields 14 -> 15
- Standalone GET /api/tasks/templates/by-region/ removed; legacy
  task_tasktemplate_regions many-to-many dropped (migration 000017).
  Region affinity now lives entirely in the template's conditions JSON

Tests
- +11 cases across task_service_test, task_handler_test, suggestion_
  service_test: template_id persistence, bulk rollback + cap + auth,
  region match / mismatch / no-ZIP / unknown-ZIP / stacks-with-others

Docs
- docs/openapi.yaml: /tasks/bulk/ + BulkCreateTasks schemas, template_id
  on TaskResponse + CreateTaskRequest, /templates/by-region/ removed

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/models/task.go

@@ -92,6 +92,12 @@ type Task struct {
 	ParentTaskID  *uint            `gorm:"column:parent_task_id;index" json:"parent_task_id"`
 	ParentTask    *Task            `gorm:"foreignKey:ParentTaskID" json:"parent_task,omitempty"`
 
+	// Template backlink — set when a task is created from a TaskTemplate
+	// (e.g. via onboarding suggestions or the browse-all catalog). Nullable
+	// so custom user tasks remain unaffected.
+	TaskTemplateID *uint         `gorm:"column:task_template_id;index" json:"task_template_id,omitempty"`
+	TaskTemplate   *TaskTemplate `gorm:"foreignKey:TaskTemplateID" json:"task_template,omitempty"`
+
 	// Completions
 	Completions   []TaskCompletion `gorm:"foreignKey:TaskID" json:"completions,omitempty"`
 

internal/models/task_template.go

@@ -16,8 +16,17 @@ type TaskTemplate struct {
 	Tags            string          `gorm:"column:tags;type:text" json:"tags"` // Comma-separated tags for search
 	DisplayOrder    int             `gorm:"column:display_order;default:0" json:"display_order"`
 	IsActive        bool            `gorm:"column:is_active;default:true;index" json:"is_active"`
-	Conditions      json.RawMessage `gorm:"column:conditions;type:jsonb;default:'{}'" json:"conditions"`
-	Regions         []ClimateRegion `gorm:"many2many:task_tasktemplate_regions;" json:"regions,omitempty"`
+	// Conditions is the JSON-encoded scoring condition set evaluated by
+	// SuggestionService. Supported keys: heating_type, cooling_type,
+	// water_heater_type, roof_type, exterior_type, flooring_primary,
+	// landscaping_type, has_pool, has_sprinkler_system, has_septic,
+	// has_fireplace, has_garage, has_basement, has_attic, property_type,
+	// climate_region_id.
+	//
+	// Climate regions used to be stored via a many-to-many with
+	// ClimateRegion; they are now driven entirely by the JSON condition
+	// above. See migration 000017 for the join-table drop.
+	Conditions json.RawMessage `gorm:"column:conditions;type:jsonb;default:'{}'" json:"conditions"`
 }
 
 // TableName returns the table name for GORM