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>

mgsh_test.go

@@ -142,7 +142,7 @@ func TestParseConfig(t *testing.T) {
 githost = 10.0.0.1
 GitPort: 22
 gituser = "deploy"
-editor = 'code'
+gitkey = 'mgit_rsa'
 ignored line without separator
 base=/tmp/src
 `
@@ -151,7 +151,7 @@ base=/tmp/src
 		"githost": "10.0.0.1",
 		"gitport": "22",
 		"gituser": "deploy",
-		"editor":  "code",
+		"gitkey":  "mgit_rsa",
 		"base":    "/tmp/src",
 	}
 	for k, want := range checks {
@@ -166,7 +166,7 @@ base=/tmp/src
 
 func TestParseConfigInlineComments(t *testing.T) {
 	rc := `
-editor = code            # fallback opener for ` + "`open`" + `
+gitkey = mgit_rsa        # fallback opener comment
 mirror = true         # ` + "`push`" + ` also mirrors via pushremote
 gitport = 22 # ssh port
 remotekey = abc#123
@@ -176,7 +176,7 @@ gitemail =        # value is only a comment
 `
 	m := parseConfig(rc)
 	checks := map[string]string{
-		"editor":    "code",
+		"gitkey":    "mgit_rsa",
 		"mirror":    "true",
 		"gitport":   "22",
 		"remotekey": "abc#123", // '#' not preceded by space stays part of the value
@@ -539,7 +539,7 @@ func TestResolveProjectConfig(t *testing.T) {
 	dir := t.TempDir()
 	global := Config{
 		Base: "/base", GitHost: "global.example", GitPort: "22", GitUser: "git",
-		GitPath: "/home/git", GitName: "Global Name", Editor: "vi",
+		GitPath: "/home/git", GitName: "Global Name", GitKey: "global_rsa",
 		Remotes: []RemoteTarget{{Name: "gitea", URL: "https://gitea.example", Key: "tok"}},
 	}
 
@@ -550,7 +550,7 @@ func TestResolveProjectConfig(t *testing.T) {
 
 	rc := `
 githost = project.example
-editor  = code
+gitkey  = project_rsa
 base    = /somewhere/else
 gitname = Project Name
 remote.hub.url = https://github.com
@@ -562,8 +562,8 @@ remote.gitea.visibility = public
 	}
 	got := resolveConfig(global, dir)
 
-	if got.GitHost != "project.example" || got.Editor != "code" {
-		t.Errorf("project overrides not applied: host=%q editor=%q", got.GitHost, got.Editor)
+	if got.GitHost != "project.example" || got.GitKey != "project_rsa" {
+		t.Errorf("project overrides not applied: host=%q gitkey=%q", got.GitHost, got.GitKey)
 	}
 	// base and the git identity stay global
 	if got.Base != "/base" {