Add branching-strategy skill with next and create actions

Version-aware branch naming (X.Y.Z.Q/{TASK_CODE}-{FEATURE}-{SEQ}),
branch creation from origin/test with origin/main fallback, and the
PR-into-test merge rule. Ships a TypeScript CLI (next, create) plus
shell modules (loggers, base, cli) run via Taskfile.

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

scripts/.scripts/base/Taskfile.yml

@@ -0,0 +1,11 @@
+# https://taskfile.dev
+
+version: "3"
+
+tasks:
+  environment:show:
+    desc: "Show environment vars"
+    cmds:
+      - |
+        ./.scripts/base/api/environment-show.sh {{ .CLI_ARGS }}
+    silent: true