Set the project license in config.env; AGPL-3.0 default only for a public GitHub project

- PROJECT_LICENSE (a Gitea license key, or none) is read, checked and never asked
- Without it AGPL-3.0 applies only when GitHub is chosen and the project is public
- The license is applied on Gitea with or without GitHub, and checked against the server first
- Plan and summary name the license and where it came from
- MIL-006 accepted; README and config.env.example document the key
- Tests: new test-license.sh; existing tests use a public project where they expect AGPL-3.0

Task: MIL-006#1
Task: MIL-006#2
Task: MIL-006#3
Task: MIL-006#4
Refs #44
Refs #45
Refs #46
Refs #50

src/lib/localproject.sh

@@ -72,7 +72,7 @@ checkout_gitea_history() {
 }
 
 # create_local_project: the directory, the git repository on main, the
-# remotes and, when GitHub is chosen, the license history. No commit is made.
+# remotes and, when a license applies, the license history. No commit is made.
 create_local_project() {
   local label="Local project" dir="${PROJECT[directory]}"
   begin_step "$label"
@@ -84,6 +84,8 @@ create_local_project() {
   ensure_remote "$dir" origin "$(origin_url)"
   if ((PROJECT[has_github])); then
     ensure_remote "$dir" github "$(github_remote_url)"
+  fi
+  if [[ -n ${PROJECT[license]} ]]; then
     checkout_gitea_history "$dir"
   fi
   finish_step "$label" "created" "$dir (origin over $(origin_protocol))"