refactor: split MLX service, introduce skill type & runtime budgets

Major restructuring of the agent stack to support content-type skills,
data-driven runtime budgets, and the new translate skill.

LLM/MLX/
- Split MLXLocalLLMService.swift (1500 → 700 lines) into Core/, Gemma4/,
  Installation/ subdirectories
- New BundledModel: LinearBudgetFormula replaces tier tables, model
  parameters fully data-driven via ModelRuntimeProfile
- New RuntimeBudgets: pure functions for text/thinking/multimodal budgets,
  zero hardcoded model IDs
- Drop adjustedTextOutputTokens prepared-subtraction (chunked prefill made
  it obsolete and triggered false-positive truncation on long prompts)

Skills/
- Add SkillType (.device / .content) metadata, parsed from SKILL.md
  frontmatter
- New translate skill (type: content, no tools) with anaphora handling
- Trim translate (4563→1804), device (2357→1680), calendar (2169→1790)
- contacts SKILL.md adds multi-turn disambiguation + cancel guidance,
  semantics owned by body not framework
- SkillRegistry validates allowed-tools against ToolRegistry at load time

Agent/
- ToolCallParser becomes registry-aware: drops tool_call names not in
  ToolRegistry or protocol set (load_skill / list_skills); ToolRegistry
  is now the single white list, validation moves to parser boundary
- Router sticky routing uses semantic user-turn boundary instead of
  fixed suffix(4); correctly handles long agent loops
- AgentEngine system prompt template differentiates device vs content
  skills with explicit invocation rules
- SYSPROMPT.md auto-migration: old single-placeholder template backed up
  to .bak when new dual-placeholder is detected
- PromptBuilder.buildLoadedSkillPrompt receives availableTools list,
  explicitly tells model which tools (or none) are callable

Tools/
- ToolRegistry split into Helpers/Stores/AppPermissions/Handlers/* for
  separation of concerns
- Mark Tools/Handlers/* with explicit allowed argument signatures

UI/
- Add long-press copy contextMenu on user and assistant bubbles
- Enable .textSelection on user bubble

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

UI/ContentView.swift

@@ -290,17 +290,33 @@ struct ContentView: View {
 
     // MARK: - Skill 快捷标签
 
+    /// chip 显示用的简写标签 (UI 表现层选择, 不影响核心数据)。
+    /// key = SkillEntry.id, value = 在 chip pill 上显示的短动作短语。
+    /// 没在表里的 skill 会 fallback 到 skill.displayName。
+    /// chip 实际发送的 prompt 仍然是 skill.samplePrompt (完整、自包含)。
+    private static let chipShortLabels: [String: String] = [
+        "calendar":  "帮我创建日程",
+        "contacts":  "帮我保存联系人",
+        "reminders": "帮我创建提醒事项",
+        "device":    "查询我手机信息",
+    ]
+
+    /// chip 隐藏名单 (UI 表现层选择): 这些 skill 不会出现在欢迎页 chip 列表里,
+    /// 但仍然在引擎里启用、可被用户手动输入触发。
+    private static let chipHiddenSkillIds: Set<String> = ["text"]
+
     private var skillChips: some View {
         ScrollView(.horizontal, showsIndicators: false) {
             HStack(spacing: 8) {
-                ForEach(engine.enabledSkillInfos, id: \.name) { skill in
+                ForEach(engine.enabledSkillInfos.filter { !Self.chipHiddenSkillIds.contains($0.name) }, id: \.name) { skill in
+                    let label = Self.chipShortLabels[skill.name] ?? skill.displayName
                     Button {
                         inputText = skill.samplePrompt
                         Task { await send() }
                     } label: {
                         HStack(spacing: 5) {
                             Image(systemName: skill.icon).font(.system(size: 11))
-                            Text(skill.displayName).font(.system(size: 12, weight: .medium))
+                            Text(label).font(.system(size: 12, weight: .medium))
                         }
                         .foregroundStyle(Theme.textSecondary)
                         .padding(.horizontal, 12)
@@ -682,9 +698,17 @@ struct UserBubble: View {
                     Text(text)
                         .font(.system(size: 15))
                         .foregroundStyle(Theme.userText)
+                        .textSelection(.enabled)
                         .padding(.horizontal, 16)
                         .padding(.vertical, 10)
                         .background(Theme.userBubble, in: UserBubbleShape())
+                        .contextMenu {
+                            Button {
+                                UIPasteboard.general.string = text
+                            } label: {
+                                Label("复制", systemImage: "doc.on.doc")
+                            }
+                        }
                 }
             }
         }
@@ -1254,6 +1278,13 @@ struct AIResponseView: View {
                         .fixedSize(horizontal: false, vertical: true)
                         .padding(.leading, 4)
                         .animation(nil, value: text)
+                        .contextMenu {
+                            Button {
+                                UIPasteboard.general.string = text
+                            } label: {
+                                Label("复制", systemImage: "doc.on.doc")
+                            }
+                        }
                 }
             }
             .animation(.easeInOut(duration: 0.3), value: block.skills.count)
@@ -1460,6 +1491,16 @@ struct SpinnerIcon: View {
 
 // MARK: - 思考动画
 
+/// 演示 chip 按钮样式: press 时 spring 缩放 + 轻微透明度变化, 让卡片有"活气"。
+struct SkillCardButtonStyle: ButtonStyle {
+    func makeBody(configuration: Configuration) -> some View {
+        configuration.label
+            .scaleEffect(configuration.isPressed ? 0.96 : 1.0)
+            .opacity(configuration.isPressed ? 0.85 : 1.0)
+            .animation(.spring(response: 0.32, dampingFraction: 0.72), value: configuration.isPressed)
+    }
+}
+
 struct ThinkingIndicator: View {
     @State private var active = 0
     let timer = Timer.publish(every: 0.45, on: .main, in: .common).autoconnect()

UI/SkillsManagerView.swift

@@ -43,7 +43,7 @@ struct SkillsManagerView: View {
                                 isExpanded: expandedSkills.contains(engine.skillEntries[i].id),
                                 onToggleExpand: { toggleExpand(engine.skillEntries[i].id) },
                                 onSave: { content in
-                                    try? engine.skillLoader.saveSkill(skillId: engine.skillEntries[i].id, content: content)
+                                    try? engine.skillRegistry.saveSkill(skillId: engine.skillEntries[i].id, content: content)
                                     engine.reloadSkills()
                                 }
                             )