fix(template): drop trailing blank from rendered postCreate.sh

Jinja's default settings keep the newline after `{% endif %}`, so the
rendered postCreate.sh ended with `bash\n\n` (a trailing blank line).
end-of-file-fixer in pre-commit flagged this, breaking lint/run and
all `test_template_*` jobs that exercise the generated project.

`{% endif -%}` strips the trailing newline; removing the blank source
line above `{% if %}` keeps the spacing tidy when add_claude is false.
Also normalises the meta repo's own .devcontainer/postCreate.sh to
match.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: gilesknap

.devcontainer/postCreate.sh

@@ -47,7 +47,5 @@ if [ -f .gitmodules ]; then
     [ -n "$missing" ] && git submodule update --init $missing
 fi
 
-
 # Install Claude Code CLI
 curl -fsSL https://claude.ai/install.sh | bash
-

template/.devcontainer/postCreate.sh.jinja

@@ -46,8 +46,7 @@ if [ -f .gitmodules ]; then
     missing=$(git submodule status | awk '/^-/ {print $2}')
     [ -n "$missing" ] && git submodule update --init $missing
 fi
-
 {% if add_claude %}
 # Install Claude Code CLI
 curl -fsSL https://claude.ai/install.sh | bash
-{% endif %}
+{% endif -%}