* refactor: auto get client ip from challenge response
Since `outip()` was not working properly on devices getting local IP addresses behind a router, we should refactor this.
After analyzing the auth process, it is shown that the challenge response includes key `client_ip` which is the real public IP address with key `ip` not specified in request.
- removed `outip()`
- added rsp key `ClientIP` to get client ip from challenge rsp
* style: trim code
* style: fix spelling issues
* refactor: create `portal_test.go` to handle portal tests separately
* feature: add `ResolveLocalClientIP()` and its test case
* optimize: resolve ClientIP locally when cant be get from challenge response
## Pull Request Overview
This PR enhances the login CLI to support a new “dorm area” and replaces the old `-x` flag with two new flags for server host (`-s`) and login type (`-t`).
- Introduces a `LoginType` enum and dynamic domain/AcID mapping in `Portal`.
- Refactors URL construction to use `go-querystring` and JSON-encoded user info.
- Updates tests and removes the hard-coded `-x` logic in `cmd/main.go`.
### Reviewed Changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.
<details>
<summary>Show a summary per file</summary>
| File | Description |
| ---------------------- | --------------------------------------------------------------- |
| portal/server_test.go | Updated tests to supply the new `loginType` parameter and use `GetUserInfo`. |
| portal/server.go | Reworked URL builders (`GetChallengeURL`, `GetLoginURL`), JSON `UserInfo`, and dynamic flags. |
| portal/portal.go | Added `LoginType`, `ToDomainAcID`, updated `NewPortal`, `GetChallenge`, and `Login` signatures. |
| cmd/main.go | Removed `-x`, added `-s`/`-t` flags, wired them through to `Portal`. |
| base64/base64.go | Fixed typo in package comment. |
| go.mod | Added `github.com/google/go-querystring` dependency. |
</details>
<details>
<summary>Comments suppressed due to low confidence (4)</summary>
**base64/base64.go:1**
* Typo in the comment: 'talbe' should be 'table'.
```
// Package base64 with customized talbe
```
**portal/portal.go:53**
* New login types (`qsh-dx`, `qshd-dx`, `qshd-cmcc`) were added but there are no unit tests verifying `ToDomainAcID` returns the correct domain and AC ID for each, or that invalid types produce an error. Consider adding tests for each mapping and an invalid case.
```
func (lt LoginType) ToDomainAcID() (string, string, error) {
```
**cmd/main.go:54**
* [nitpick] The flag variables `s` and `t` are not descriptive. Consider renaming them to `server` and `loginType` (or similar) to improve clarity for users and maintainers.
```
s := flag.String("s", portal.PortalServerIPQsh, "login host")
```
**cmd/main.go:106**
* The call to `netip.ParseAddr` requires importing the `net/netip` package, but `netip` is not imported. Add `import "net/netip"` to fix the compile error.
```
_, err := netip.ParseAddr(*s)
```
</details>
---------
Co-authored-by: 源文雨 <41315874+fumiama@users.noreply.github.com>
