refactor: remove features beyond the UX plan

Drop additions that the UX plan does not ask for:

- the interactive label edit form; label edit now requires a flag
- label clone and the skip mode of label creation it needed
- repo rename rewriting the Git remote or tea.repository; it now
  warns that the remote still points to the old name
- the extra "source" remote on clones of pull mirrors
- run artifact download, which duplicates run download --zip
- 256-color and 24-bit label swatches; colors stay ANSI 16
- config list --show-source (config get keeps it)
- the membership and access GETs before team member/repo add and
  remove; Gitea's PUT and DELETE are idempotent

label edit/delete keep --by-name: it is the only way to address a
label whose name is a number that is also another label's ID.

Signed-off-by: bircni <bircni@icloud.com>

internal/terminal/table_test.go

@@ -98,7 +98,7 @@ func TestTable(t *testing.T) {
 			[][]Cell{{{Text: "7", Link: "https://example.org/7"}, {Text: "bug", Color: "ff0000", Link: "https://example.org/bug"}, {Text: "open", Color: "green", Bold: true}}, row("12", "feature", "closed")},
 			Display{TTY: true, Color: true, Links: true},
 			"\x1b[90mID\x1b[0m  \x1b[90mNAME\x1b[0m     \x1b[90mSTATE\x1b[0m\n" +
-				"\x1b]8;;https://example.org/7\x1b\\7\x1b]8;;\x1b\\   \x1b[38;5;196mbug\x1b[0m      \x1b[1m\x1b[32mopen\x1b[0m\x1b[0m\n" +
+				"\x1b]8;;https://example.org/7\x1b\\7\x1b]8;;\x1b\\   bug      \x1b[1m\x1b[32mopen\x1b[0m\x1b[0m\n" +
 				"12  feature  closed\n",
 		},
 		{
@@ -109,11 +109,11 @@ func TestTable(t *testing.T) {
 			"\x1b]8;;https://example.org/7\x1b\\7\x1b]8;;\x1b\\  bug\n",
 		},
 		{
-			"writes 24-bit color on true-color terminals",
+			"leaves hex colors plain",
 			nil,
 			[][]Cell{{{Text: "bug", Color: "#ff0000"}, {Text: "old", Muted: true}}},
-			Display{TTY: true, Color: true, TrueColor: true},
-			"\x1b[38;2;255;0;0mbug\x1b[0m  \x1b[90mold\x1b[0m\n",
+			Display{TTY: true, Color: true},
+			"bug  \x1b[90mold\x1b[0m\n",
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {