fix: make managed SSH sessions fast and resilient

Managed SSH project selection repeatedly activated the remote Host and could
leave idle ACP bindings rejected as stale-controller after a controller
generation change. Host environment updates also coupled project state to
component installation evidence and presented a crowded control surface.

Project selection is now local-only, one Host connection serves compatible
project and conversation callers, idle bindings are safely replaced only
after proven controller takeover, and active prompts keep exact resume/replay.
Remote environment setup now uses explicit signed compound package
preparation with bounded transfer, rollback, recovery, and clearer settings.

Managed Hosts must be updated to separately distributed Agent 0.11.6 before
the daemon-side controller recovery fix takes effect. Desktop packages do not
embed the Agent or remote Runtime, and existing project data is preserved.

Release note: 托管 SSH 项目切换不再重复连接，同一 Host 可顺畅承载多个项目和对话；同时修复重连后的 stale-controller，并优化远程环境安装、更新与状态布局。

src/main/remote-agent/remote-environment-operation-store.ts

@@ -0,0 +1,141 @@
+import { createHash } from 'node:crypto'
+import { readFile, rm } from 'node:fs/promises'
+import { join, resolve } from 'node:path'
+import {
+  isMissingFileError,
+  writeJsonFileAtomically
+} from '../settings-file-utils'
+
+const MAXIMUM_RECORD_BYTES = 64 * 1024
+const OPERATION_ID_PATTERN =
+  /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/u
+const SHA256_PATTERN = /^[a-f0-9]{64}$/u
+
+export type PendingRemoteEnvironmentOperation = {
+  version: 1
+  hostId: string
+  targetIdentity: string
+  operationId: string
+  size: number
+  sha256: string
+  urls: readonly string[]
+}
+
+export class RemoteEnvironmentOperationStore {
+  readonly #directory: string
+
+  constructor(userDataPath: string) {
+    this.#directory = resolve(
+      userDataPath,
+      'remote-components',
+      'pending-environment-operations'
+    )
+  }
+
+  async load(
+    hostId: string
+  ): Promise<PendingRemoteEnvironmentOperation | undefined> {
+    const path = this.#path(hostId)
+    let bytes: Buffer
+    try {
+      bytes = await readFile(path)
+    } catch (error) {
+      if (isMissingFileError(error)) {
+        return undefined
+      }
+      throw error
+    }
+    if (bytes.byteLength > MAXIMUM_RECORD_BYTES) {
+      throw new Error('远程环境恢复记录超过大小限制')
+    }
+    let value: unknown
+    try {
+      value = JSON.parse(
+        new TextDecoder('utf-8', { fatal: true }).decode(bytes)
+      )
+    } catch (error) {
+      throw new Error('远程环境恢复记录无效', {
+        cause: error
+      })
+    }
+    return parsePendingOperation(value, hostId)
+  }
+
+  save(operation: PendingRemoteEnvironmentOperation): Promise<void> {
+    return writeJsonFileAtomically(
+      this.#path(operation.hostId),
+      parsePendingOperation(operation, operation.hostId)
+    )
+  }
+
+  remove(hostId: string): Promise<void> {
+    return rm(this.#path(hostId), { force: true })
+  }
+
+  #path(hostId: string): string {
+    if (
+      !hostId ||
+      hostId.length > 512 ||
+      /[\p{Cc}\p{Cs}\u2028\u2029\ufffd]/u.test(hostId)
+    ) {
+      throw new Error('远程环境恢复 Host ID 无效')
+    }
+    const name = createHash('sha256')
+      .update(hostId)
+      .digest('hex')
+    return join(this.#directory, `${name}.json`)
+  }
+}
+
+function parsePendingOperation(
+  value: unknown,
+  expectedHostId: string
+): PendingRemoteEnvironmentOperation {
+  if (
+    typeof value !== 'object' ||
+    value === null ||
+    Object.keys(value).sort().join('\0') !==
+      [
+        'hostId',
+        'operationId',
+        'sha256',
+        'size',
+        'targetIdentity',
+        'urls',
+        'version'
+      ].sort().join('\0')
+  ) {
+    throw new Error('远程环境恢复记录无效')
+  }
+  const record = value as Record<string, unknown>
+  if (
+    record.version !== 1 ||
+    record.hostId !== expectedHostId ||
+    typeof record.targetIdentity !== 'string' ||
+    !SHA256_PATTERN.test(record.targetIdentity) ||
+    typeof record.operationId !== 'string' ||
+    !OPERATION_ID_PATTERN.test(record.operationId) ||
+    !Number.isSafeInteger(record.size) ||
+    Number(record.size) <= 0 ||
+    typeof record.sha256 !== 'string' ||
+    !SHA256_PATTERN.test(record.sha256) ||
+    !Array.isArray(record.urls) ||
+    record.urls.length > 4 ||
+    record.urls.some(
+      (url) =>
+        typeof url !== 'string' ||
+        Buffer.byteLength(url, 'utf8') > 4_096
+    )
+  ) {
+    throw new Error('远程环境恢复记录无效')
+  }
+  return {
+    version: 1,
+    hostId: expectedHostId,
+    targetIdentity: record.targetIdentity,
+    operationId: record.operationId,
+    size: Number(record.size),
+    sha256: record.sha256,
+    urls: [...record.urls] as string[]
+  }
+}