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

tests/test-security.sh

@@ -19,10 +19,10 @@ test_full_run_with_github() {
   after="$(listing)"
   assert_status "full run" 0 "$STATUS"
   assert_contains "dry run" "$OUT" "Dry run: nothing was created"
-  assert_contains "plan" "$OUT" "create (private) with the AGPL-3.0 license"
+  assert_contains "plan" "$OUT" "create (private), empty"
   assert_contains "Gitea link derived from config" "$OUT" "https://git.example.test/TirSystem/my-app"
   assert_contains "GitHub link uses the chosen organization" "$OUT" "https://github.com/acme-org/my-app"
-  assert_contains "AGPL noted" "$OUT" "AGPL license applied"
+  assert_contains "no default license for a private project" "$OUT" "License      : none (no default for a private project)"
   assert_contains "credential state" "$OUT" "GITEA_TOKEN set, GITHUB_PAT set"
   assert_not_contains "no Gitea token in output" "$OUT$ERR" "$FAKE_GITEA_TOKEN"
   assert_not_contains "no GitHub token in output" "$OUT$ERR" "$FAKE_GITHUB_PAT"