Add gitignore-claude template and wire into registration flows

Introduce scripts/project_rules/gitignore-claude.template with the fleet
pattern that tracks .claude/rules/ while ignoring machine-local Claude state.
ensure_gitignore_claude_rules.py applies it during statehub register,
register_project.sh, and update_agent_instruction_files fleet regen.

scripts/register_project.sh

@@ -147,6 +147,9 @@ if [[ "$ADDITIONAL" != "true" ]]; then
         echo "==> SCOPE.md already exists — skipping."
     fi
 
+    echo "==> Ensuring .gitignore tracks .claude/rules/ ..."
+    python3 "$SCRIPT_DIR/ensure_gitignore_claude_rules.py" "$PROJECT_PATH"
+
     if [[ "$CODEX_MODE" == "true" ]]; then
         # ── 5b: Codex — write AGENTS.md from HTTP-API template ────────────────
         AGENTS_MD="$PROJECT_PATH/AGENTS.md"