feat: add polecat lifecycle management

Types:
- Polecat: worker agent with state, clone, branch, issue
- State: idle/active/working/done/stuck
- Summary: concise status view

Manager operations:
- Add: clone rig, create branch, init state
- Remove: delete polecat (checks for uncommitted changes)
- List: enumerate all polecats
- Get: retrieve specific polecat

State management:
- SetState: update lifecycle state
- AssignIssue: assign work (sets StateWorking)
- ClearIssue: remove assignment (sets StateIdle)
- Wake: idle → active
- Sleep: active → idle

State persisted to polecats/<name>/state.json

Closes gt-u1j.8

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/polecat/types.go

@@ -0,0 +1,77 @@
+// Package polecat provides polecat lifecycle management.
+package polecat
+
+import "time"
+
+// State represents the current state of a polecat.
+type State string
+
+const (
+	// StateIdle means the polecat is not actively working.
+	StateIdle State = "idle"
+
+	// StateActive means the polecat session is running but not assigned work.
+	StateActive State = "active"
+
+	// StateWorking means the polecat is actively working on an issue.
+	StateWorking State = "working"
+
+	// StateDone means the polecat has completed its assigned work.
+	StateDone State = "done"
+
+	// StateStuck means the polecat needs assistance.
+	StateStuck State = "stuck"
+)
+
+// IsAvailable returns true if the polecat can be assigned new work.
+func (s State) IsAvailable() bool {
+	return s == StateIdle || s == StateActive
+}
+
+// IsWorking returns true if the polecat is currently working.
+func (s State) IsWorking() bool {
+	return s == StateWorking
+}
+
+// Polecat represents a worker agent in a rig.
+type Polecat struct {
+	// Name is the polecat identifier.
+	Name string `json:"name"`
+
+	// Rig is the rig this polecat belongs to.
+	Rig string `json:"rig"`
+
+	// State is the current lifecycle state.
+	State State `json:"state"`
+
+	// ClonePath is the path to the polecat's clone of the rig.
+	ClonePath string `json:"clone_path"`
+
+	// Branch is the current git branch.
+	Branch string `json:"branch"`
+
+	// Issue is the currently assigned issue ID (if any).
+	Issue string `json:"issue,omitempty"`
+
+	// CreatedAt is when the polecat was created.
+	CreatedAt time.Time `json:"created_at"`
+
+	// UpdatedAt is when the polecat was last updated.
+	UpdatedAt time.Time `json:"updated_at"`
+}
+
+// Summary provides a concise view of polecat status.
+type Summary struct {
+	Name  string `json:"name"`
+	State State  `json:"state"`
+	Issue string `json:"issue,omitempty"`
+}
+
+// Summary returns a Summary for this polecat.
+func (p *Polecat) Summary() Summary {
+	return Summary{
+		Name:  p.Name,
+		State: p.State,
+		Issue: p.Issue,
+	}
+}