feat(workflows): wire TaskUnit/Orchestrator activities, add k8s deploy manifests

Implements real activity-calling logic in OrchestratorWorkflow and
TaskUnitWorkflow (previously stubs), adds GitDiffActivity, and expands
PlanningActivity's I/O to carry repo path and prior task results.

Adds k8s/ deployment manifests (worker Deployment, orchestrator Job,
Kustomize base) for the poimen-workflows Temporal worker, using a
dedicated Kubernetes namespace `poimen` and Temporal namespace
`poimen-harness` rather than sharing the Temporal server's own
`temporal`/`production` namespaces.

action/planner.go

@@ -11,9 +11,11 @@ import (
 
 // PlanningInput is input to PlanningActivity.
 type PlanningInput struct {
-	Config      statemachine.OrchestratorConfig
-	BoardState  string // JSON or markdown of task board
-	Milestone   string
+	Config        statemachine.OrchestratorConfig
+	BoardState    string                            // JSON or markdown of task board
+	RepoPath      string                            // Path to target repository
+	Milestone     string                            // e.g., "T0"
+	TaskResults   []statemachine.TaskUnitOutput     // Results from completed tasks
 }
 
 // TaskDispatch represents a dispatched task.
@@ -25,8 +27,9 @@ type TaskDispatch struct {
 
 // PlanningOutput is the output of PlanningActivity.
 type PlanningOutput struct {
-	Tasks                []TaskDispatch
-	SubmilestoneComplete bool
+	TasksToDispatch        []string // Task IDs to dispatch in this cycle
+	CompletedBranches      []string // Branches to squash merge (when milestone complete)
+	SubmilestoneComplete   bool     // Whether the milestone is complete
 }
 
 // PlanningActivity calls the Planner LLM to decide which tasks to dispatch.
@@ -81,7 +84,8 @@ func PlanningActivity(ctx context.Context, in PlanningInput) (PlanningOutput, er
 	// This is a stub that allows the test to verify the activity is called
 	_ = response
 	return PlanningOutput{
-		Tasks:                []TaskDispatch{},
+		TasksToDispatch:      []string{},
+		CompletedBranches:    []string{},
 		SubmilestoneComplete: false,
 	}, nil
 }