fix(mount): start core only for local remotes

[Suyunmeng]

Summary / 摘要

• Start the local OpenList Core before automatic Rclone mounts only when an enabled mount targets a loopback WebDAV endpoint.
  仅当已启用的自动挂载目标为回环 WebDAV 端点时，才在挂载前启动本地 OpenList Core。

• Keep remote OpenList mounts independent from the local Core auto-launch setting.
  使远端 OpenList 挂载不再受本地 Core 自动启动行为影响。

• Read each remote URL from the effective rclone configuration so custom or externally edited configurations are handled correctly.
  从实际生效的 Rclone 配置中读取各 remote 的 URL，正确支持自定义或外部修改过的配置。

• Add coverage for localhost, IPv4 loopback, IPv6 loopback, remote, and invalid URLs.
  为 localhost、IPv4 回环、IPv6 回环、远端及无效 URL 添加覆盖。

• This PR has breaking changes.
  / 此 PR 包含破坏性变更。

• This PR changes public API, config, storage format, or migration behavior.
  / 此 PR 修改了公开 API、配置、存储格式或迁移行为。

• This PR requires corresponding changes in related repositories.
  / 此 PR 需要关联仓库同步修改。

Related repository PRs / 关联仓库 PR:

• OpenList-Frontend:
• OpenList-Docs:

Related Issues / 关联 Issue

Closes #195

Testing / 测试

• git diff --check main...HEAD
• cargo fmt --check
  / 未执行：本机 rustup 未安装 Rust toolchain。
• Related Rust unit tests
  / 未执行：本机 rustup 未安装 Rust toolchain。
• Static review of local, remote, mixed remote, and auto_launch startup paths.
  / 已静态复查本地、远端、混合 remote 及 auto_launch 启动路径。

Checklist / 检查清单

• I have read CONTRIBUTING.
  / 我已阅读 CONTRIBUTING。
• I confirm this contribution follows the repository license, contribution policy, and code of conduct.
  / 我确认此贡献符合仓库许可证、贡献规范和行为准则。
• I have formatted the changed code with gofmt, go fmt, or prettier where applicable.
  / 我已按适用情况使用 gofmt、go fmt 或 prettier 格式化变更代码。
• I have requested review from relevant maintainers or code owners where applicable.
  / 我已在适用情况下请求相关维护者或代码所有者审查。

AI Disclosure / AI 使用声明

• This PR includes AI-assisted content.
  / 此 PR 包含 AI 辅助内容。

Tools used / 使用工具:

• Claude

Usage scope / 使用范围:

• Code generation / 代码生成

• Tests / 测试

• Review assistance / 审查辅助

• I have reviewed and validated all AI-assisted content included in this PR.
  / 我已审核并验证此 PR 中的所有 AI 辅助内容。

• I have ensured that all AI-assisted commits include Co-Authored-By attribution.
  / 我已确保所有 AI 辅助提交都包含 Co-Authored-By 归属信息。

• I can reproduce all AI-assisted content included in this PR without any AI tools.
  / 我可以在没有任何 AI 工具的情况下重现此 PR 中包含的所有 AI 辅助内容。