feat: 添加 /goal 命令，支持长时间运行任务的目标管理 (#1222)

* feat: 添加 /goal 命令，支持长时间运行任务的目标管理

从 Codex 项目移植 /goal 命令到 Claude Code，实现：
- Goal 状态管理模块（active/paused/budget_limited/complete）
- /goal 斜杠命令（set/clear/pause/resume/complete）
- Goal 模型工具（get/set/complete）
- Continuation prompt 自动注入系统提示
- Token 用量自动追踪

Co-Authored-By: mimo-v2.5-pro <XiaomiMiMo@claude-code-best.win>

* fix: goal 状态改为 session-scoped，避免多会话泄漏

将 currentGoal 单例替换为 Map<string, GoalState>，按 sessionId 隔离，
遵循 sessionIngress.ts 的模式。所有函数支持可选 sessionId 参数。

Co-Authored-By: mimo-v2.5-pro <XiaomiMiMo@claude-code-best.win>

* fix: 对 goal 的 tokenBudget/tokensUsed 添加数值校验

setGoal 中 tokenBudget 非 finite 或负数时归零；
updateGoalTokens 中 usage 非 finite 或负数时归零。

Co-Authored-By: mimo-v2.5-pro <XiaomiMiMo@claude-code-best.win>

* fix: 暂停期间 goal 时间不再继续计数

新增 pausedAt/accumulatedActiveMs 字段，pauseGoal 累积已活跃时间，
resumeGoal 重置 startTime，计时统一使用 getActiveElapsedMs()。

Co-Authored-By: mimo-v2.5-pro <XiaomiMiMo@claude-code-best.win>

---------

Co-authored-by: mimo-v2.5-pro <XiaomiMiMo@claude-code-best.win>

src/services/goal/goalState.ts

@@ -0,0 +1,156 @@
+import { getSessionId } from '../../bootstrap/state.js'
+
+export type GoalStatus = 'active' | 'paused' | 'budget_limited' | 'complete'
+
+export type GoalState = {
+  objective: string
+  status: GoalStatus
+  tokenBudget: number | null
+  tokensUsed: number
+  startTime: number
+  pausedAt: number | null
+  accumulatedActiveMs: number
+}
+
+const goals: Map<string, GoalState> = new Map()
+
+export function getGoal(sessionId?: string): GoalState | null {
+  return goals.get(sessionId ?? getSessionId()) ?? null
+}
+
+export function setGoal(
+  objective: string,
+  tokenBudget?: number,
+  sessionId?: string,
+): GoalState {
+  const validBudget =
+    tokenBudget !== undefined &&
+    Number.isFinite(tokenBudget) &&
+    tokenBudget >= 0
+      ? tokenBudget
+      : null
+  const state: GoalState = {
+    objective,
+    status: 'active',
+    tokenBudget: validBudget,
+    tokensUsed: 0,
+    startTime: Date.now(),
+    pausedAt: null,
+    accumulatedActiveMs: 0,
+  }
+  goals.set(sessionId ?? getSessionId(), state)
+  return state
+}
+
+export function clearGoal(sessionId?: string): void {
+  goals.delete(sessionId ?? getSessionId())
+}
+
+export function pauseGoal(sessionId?: string): boolean {
+  const goal = getGoal(sessionId)
+  if (!goal || goal.status !== 'active') return false
+  goal.accumulatedActiveMs += Date.now() - goal.startTime
+  goal.pausedAt = Date.now()
+  goal.status = 'paused'
+  return true
+}
+
+export function resumeGoal(sessionId?: string): boolean {
+  const goal = getGoal(sessionId)
+  if (!goal || goal.status !== 'paused') return false
+  goal.pausedAt = null
+  goal.startTime = Date.now()
+  goal.status = 'active'
+  return true
+}
+
+export function completeGoal(sessionId?: string): boolean {
+  const goal = getGoal(sessionId)
+  if (!goal) return false
+  goal.status = 'complete'
+  return true
+}
+
+export function updateGoalTokens(usage: number, sessionId?: string): void {
+  const goal = getGoal(sessionId)
+  if (!goal || goal.status !== 'active') return
+  const validUsage = Number.isFinite(usage) && usage >= 0 ? usage : 0
+  goal.tokensUsed += validUsage
+  if (goal.tokenBudget !== null && goal.tokensUsed >= goal.tokenBudget) {
+    goal.status = 'budget_limited'
+  }
+}
+
+export function getActiveElapsedMs(goal: GoalState): number {
+  const ongoing =
+    goal.status === 'active' && goal.pausedAt === null
+      ? Date.now() - goal.startTime
+      : 0
+  return goal.accumulatedActiveMs + ongoing
+}
+
+export function getGoalContinuationPrompt(sessionId?: string): string | null {
+  const goal = getGoal(sessionId)
+  if (!goal || goal.status !== 'active') return null
+
+  const elapsedSeconds = Math.floor(getActiveElapsedMs(goal) / 1000)
+  const budgetDisplay =
+    goal.tokenBudget !== null ? `${goal.tokenBudget}` : 'unlimited'
+  const remainingDisplay =
+    goal.tokenBudget !== null
+      ? `${Math.max(0, goal.tokenBudget - goal.tokensUsed)}`
+      : 'unlimited'
+
+  return `Continue working toward the active goal.
+
+<objective>
+${goal.objective}
+</objective>
+
+Budget:
+- Time spent: ${elapsedSeconds} seconds
+- Tokens used: ${goal.tokensUsed}
+- Token budget: ${budgetDisplay}
+- Tokens remaining: ${remainingDisplay}
+
+Avoid repeating work that is already done. Choose the next concrete action toward the objective.
+
+Before deciding that the goal is achieved, perform a completion audit:
+- Restate the objective as concrete deliverables or success criteria.
+- Inspect relevant files, command output, test results, or other real evidence.
+- Do not accept proxy signals as completion by themselves.
+- Treat uncertainty as not achieved; do more verification or continue the work.
+- Only mark the goal achieved when the objective has actually been achieved and no required work remains.
+
+If the objective is achieved, call the goal tool with action "complete" so usage accounting is preserved.`
+}
+
+export function formatGoalStatus(sessionId?: string): string {
+  const goal = getGoal(sessionId)
+  if (!goal) return 'No active goal.'
+
+  const elapsed = Math.floor(getActiveElapsedMs(goal) / 1000)
+  const minutes = Math.floor(elapsed / 60)
+  const seconds = elapsed % 60
+  const timeStr = minutes > 0 ? `${minutes}m ${seconds}s` : `${seconds}s`
+
+  const statusLabel: Record<GoalStatus, string> = {
+    active: 'Active',
+    paused: 'Paused',
+    budget_limited: 'Budget Limited',
+    complete: 'Complete',
+  }
+
+  const lines = [
+    `Goal: ${goal.objective}`,
+    `Status: ${statusLabel[goal.status]}`,
+    `Time: ${timeStr}`,
+    `Tokens: ${goal.tokensUsed}${goal.tokenBudget !== null ? ` / ${goal.tokenBudget}` : ''}`,
+  ]
+
+  return lines.join('\n')
+}
+
+export function clearAllGoals(): void {
+  goals.clear()
+}