feat: sync upstream pi-mono (386 commits)

从上游 badlogic/pi-mono 同步 386 个提交，手动解决所有冲突：

保留 SproutClaw 独有功能：
- RPC: reload 命令、bash 流式输出、get_extensions 命令
- settings-manager: showChangelogOnStartup 设置
- agent-session: turnIndex getter
- 移除 pi 版本检查通知（interactive-mode）
- skills 系统、启动脚本、自定义工具脚本

直接采用上游版本：
- packages/ai 模型列表及测试文件
- packages/coding-agent 文档
- 其余未冲突的全部上游代码

升级 @mistralai/mistralai 至 2.2.6（修复 promptCacheKey 类型错误）

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

packages/coding-agent/docs/rpc.md

@@ -13,6 +13,7 @@ pi --mode rpc [options]
 Common options:
 - `--provider <name>`: Set the LLM provider (anthropic, openai, google, etc.)
 - `--model <pattern>`: Model pattern or ID (supports `provider/id` and optional `:<thinking>`)
+- `--name <name>` / `-n <name>`: Set the session display name at startup
 - `--no-session`: Disable session persistence
 - `--session-dir <path>`: Custom session storage directory
 
@@ -373,11 +374,14 @@ Response:
     "summary": "Summary of conversation...",
     "firstKeptEntryId": "abc123",
     "tokensBefore": 150000,
+    "estimatedTokensAfter": 32000,
     "details": {}
   }
 }
 ```
 
+`estimatedTokensAfter` is a heuristic estimate over the rebuilt message context immediately after compaction, not a provider-exact token count.
+
 #### set_auto_compaction
 
 Enable or disable automatic compaction when context is nearly full.
@@ -702,7 +706,7 @@ Response:
 }
 ```
 
-The current session name is available via `get_state` in the `sessionName` field.
+The current session name is available via `get_state` in the `sessionName` field. To set the initial name when starting RPC mode, pass `--name <name>` or `-n <name>` to the `pi --mode rpc` process.
 
 ### Commands
 
@@ -931,6 +935,7 @@ The `reason` field is `"manual"`, `"threshold"`, or `"overflow"`.
     "summary": "Summary of conversation...",
     "firstKeptEntryId": "abc123",
     "tokensBefore": 150000,
+    "estimatedTokensAfter": 32000,
     "details": {}
   },
   "aborted": false,
@@ -1010,7 +1015,7 @@ Some `ExtensionUIContext` methods are not supported or degraded in RPC mode beca
 - `getTheme()` returns `undefined`
 - `setTheme()` returns `{ success: false, error: "..." }`
 
-Note: `ctx.hasUI` is `true` in RPC mode because the dialog and fire-and-forget methods are functional via the extension UI sub-protocol.
+Note: `ctx.mode` is `"rpc"` and `ctx.hasUI` is `true` in RPC mode because the dialog and fire-and-forget methods are functional via the extension UI sub-protocol. Use `ctx.mode === "tui"` to guard TUI-specific features like `custom()` that require a real terminal.
 
 ### Extension UI Requests (stdout)