Improve DNS upstream table

[yubiuser]

What does this PR aim to accomplish?:
This PR does two things: 1) fix the DNS upstream table 2) improve the custom upstream input box

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Fix DNS upstream table.

Main fix: DNSupstreamsTable does not exist, but DNSupstreamsTable-plan, DNSupstreamsTable-doh and DNSupstreamsTable-dot.

Additionally, if no title is set (DNS server address), return early.
Additionally 2: also break on Windows CRLF and remove empty entries from the input field.

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The last commit improves the custom upstream input box to really only show entries that do not match any selected entry from the table above. I always found it confusing that the "custom upstream" box also contained non-custom but selected upstreams. It now keeps both things separate and only merged them before the list of upstreams is send to the API

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[Copilot]

Pull request overview

Fixes the upstream DNS selection UI logic by targeting the correct upstream tables across Plain/DoT/DoH tabs and improving parsing of the custom-upstreams textarea.

Changes:

• Adds a stable wrapper ID (DNSupstreamTabs) around the upstream tabs to scope DOM queries correctly.
• Updates checkbox-change handling to iterate over all upstream tables (plain/dot/doh) instead of a non-existent #DNSupstreamsTable.
• Improves textarea splitting for Windows CRLF and filters out empty lines (with a remaining whitespace-only edge case noted in review).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
settings-dns.lp	Adds id="DNSupstreamTabs" to the upstream tabs container so JS can reliably scope table/checkbox queries.
scripts/js/settings-dns.js	Fixes checkbox iteration selector to cover all upstream tables and improves newline parsing of the custom upstreams textarea.

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[yubiuser]

The last commit improves the custom upstream input box to really only show entries that do not match any selected entry from the table above. I always found it confusing that the "custom upstream" box also contained non-custom but selected upstreams. It now keeps both things separate and only merged them before the list of upstreams is send to the API

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

Suppressed comments (2)

scripts/js/settings-dns.js:12

• Grammar in the comment: “manual entered” should be “manually entered”.

// Get the manual entered upstream servers from the textarea

scripts/js/settings.js:146

• For robustness and consistency with other textarea parsing in this codebase (e.g., settings-dns.js/settings-dhcp.js), consider splitting textarea values with /\r?\n/ instead of "\n" so CRLF inputs don’t leave trailing "\r" characters in array entries.

    if ($(this).is("textarea")) {
      value = $(this).val();
      value = value === "" ? [] : value.split("\n");

      // On DNS settings page, upstream table selections are merged at save
      // time so the textarea can remain manual-only in the UI.
      if (key === "dns.upstreams" && typeof globalThis.getMergedDNSupstreams === "function") {
        value = globalThis.getMergedDNSupstreams(value);