feat: workspace creation with seed files and collision handling

Create function produces full workspace layout (task.yaml, CLAUDE.md, notes.md, context/, output/, logs/). Seed files only written if missing. Collision suffixing tested.

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

internal/seed/templates.go

@@ -0,0 +1,47 @@
+package seed
+
+import "fmt"
+
+// ClaudeMD returns the advisory CLAUDE.md content for a workspace.
+func ClaudeMD(slug, category, workspacePath string) string {
+	return fmt.Sprintf(`# Task Workspace: %s
+
+This is a ctask-managed workspace.
+
+- **Category:** %s
+- **Workspace:** %s
+
+## Scope
+
+This workspace is scoped to a single task. Keep work focused on the task described in notes.md.
+
+## Files
+
+- task.yaml — Task metadata (machine-managed, do not edit)
+- notes.md — Task log (human/agent-managed)
+- context/ — Reference documents (user-managed)
+- output/ — Task deliverables and artifacts
+- logs/ — Session logs (reserved for future use)
+`, slug, category, workspacePath)
+}
+
+// NotesMD returns the skeleton notes.md content.
+func NotesMD(title string) string {
+	return fmt.Sprintf(`# %s
+
+## Purpose
+
+
+
+## Constraints
+
+
+
+## Actions
+
+
+
+## Results
+
+`, title)
+}