ci: docker_tag=ext

Add .gitmodules for all 4NK projects
- Configure all projects as Git submodules
- Set branch ext for all submodules
- Enable proper submodule management

.gitmodules

@@ -0,0 +1,44 @@
+[submodule "lecoffre_node"]
+	path = lecoffre_node
+	url = git@git.4nkweb.com:4nk/lecoffre_node.git
+	branch = ext
+[submodule "sdk_relay"]
+	path = sdk_relay
+	url = git@git.4nkweb.com:4nk/sdk_relay.git
+	branch = ext
+[submodule "sdk_signer"]
+	path = sdk_signer
+	url = git@git.4nkweb.com:4nk/sdk_signer.git
+	branch = ext
+[submodule "sdk_storage"]
+	path = sdk_storage
+	url = git@git.4nkweb.com:4nk/sdk_storage.git
+	branch = ext
+[submodule "sdk_client"]
+	path = sdk_client
+	url = git@git.4nkweb.com:4nk/sdk_client.git
+	branch = ext
+[submodule "sdk_common"]
+	path = sdk_common
+	url = git@git.4nkweb.com:4nk/sdk_common.git
+	branch = ext
+[submodule "sdk-signer-client"]
+	path = sdk-signer-client
+	url = git@git.4nkweb.com:4nk/sdk-signer-client.git
+	branch = ext
+[submodule "ihm_client"]
+	path = ihm_client
+	url = git@git.4nkweb.com:4nk/ihm_client.git
+	branch = ext
+[submodule "lecoffre-back-mini"]
+	path = lecoffre-back-mini
+	url = git@git.4nkweb.com:4nk/lecoffre-back-mini.git
+	branch = ext
+[submodule "lecoffre-front"]
+	path = lecoffre-front
+	url = git@git.4nkweb.com:4nk/lecoffre-front.git
+	branch = ext
+[submodule "doc_api"]
+	path = doc_api
+	url = git@git.4nkweb.com:4nk/doc_api.git
+	branch = ext