Remove the view command and the editor setting with it

`view` was the last user of `editor`, so leaving the setting behind would
have made it exactly what `gitkey` was until recently: documented,
parsed, and doing nothing. It is gone from the struct, the template, the
environment, `config -k` and the settings table.

Both names are free for aliases now, as `open` already was.

The tests that used `editor` as their example of a project-overridable
setting use `gitkey` instead, which is the same kind of thing and still
exists.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

completion.go

@@ -45,14 +45,13 @@ func runeSuffixes(cands []string, prefix string) ([][]rune, int) {
 }
 
 // builtinCompleter is the command tree. Command names complete at the start of
-// the line; cd/view complete local project names; clone/show complete
+// the line; cd completes local project names; clone/show complete
 // repository names cached from the git server; checkout/tag complete branch and
 // tag names; pushremote/release complete mirror targets; dist completes
 // filesystem paths.
 func builtinCompleter() *readline.PrefixCompleter {
 	return readline.NewPrefixCompleter(
 		readline.PcItem("cd", readline.PcItemDynamic(dynLocalProjects)),
-		readline.PcItem("view", readline.PcItemDynamic(dynLocalProjects)),
 		readline.PcItem("clone",
 			readline.PcItem("-a", readline.PcItemDynamic(dynServerArchives)),
 			readline.PcItemDynamic(dynServerRepos),