refactor: split types.ts into domain modules (phase 4, step 1)

Split 1,443-line types.ts into 14 focused domain files under src/types/:
common.ts, session.ts, task.ts, app-state.ts, respawn.ts, ralph.ts,
api.ts, lifecycle.ts, run-summary.ts, tools.ts, teams.ts, push.ts,
plan.ts, and index.ts barrel.

Moved PlanItem interface from plan-orchestrator.ts into types/plan.ts
to break circular dependency. Original types.ts replaced with barrel
re-export — zero changes to 36 import sites.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/types/task.ts

@@ -0,0 +1,60 @@
+/**
+ * @fileoverview Task queue type definitions
+ */
+
+/** Status of a task in the queue */
+export type TaskStatus = 'pending' | 'running' | 'completed' | 'failed';
+
+/**
+ * Definition of a task to be executed
+ */
+export interface TaskDefinition {
+  /** Unique task identifier */
+  id: string;
+  /** Prompt to send to Claude */
+  prompt: string;
+  /** Working directory for task execution */
+  workingDir: string;
+  /** Priority level (higher = processed first) */
+  priority: number;
+  /** IDs of tasks that must complete first */
+  dependencies: string[];
+  /** Custom phrase to detect task completion */
+  completionPhrase?: string;
+  /** Timeout in milliseconds */
+  timeoutMs?: number;
+}
+
+/**
+ * Full state of a task including execution details
+ */
+export interface TaskState {
+  /** Unique task identifier */
+  id: string;
+  /** Prompt sent to Claude */
+  prompt: string;
+  /** Working directory for task execution */
+  workingDir: string;
+  /** Priority level (higher = processed first) */
+  priority: number;
+  /** IDs of tasks that must complete first */
+  dependencies: string[];
+  /** Custom phrase to detect task completion */
+  completionPhrase?: string;
+  /** Timeout in milliseconds */
+  timeoutMs?: number;
+  /** Current task status */
+  status: TaskStatus;
+  /** ID of session running this task, null if not assigned */
+  assignedSessionId: string | null;
+  /** Timestamp when task was created */
+  createdAt: number;
+  /** Timestamp when task started executing */
+  startedAt: number | null;
+  /** Timestamp when task completed */
+  completedAt: number | null;
+  /** Captured output from Claude */
+  output: string;
+  /** Error message if task failed */
+  error: string | null;
+}