Declare Standalone example project as Public explicitly #84

Problem

src/config/standalone.tfvars declares landing_zones["public-exmpl"] without corporate, and does not configure connectivity. The root input defaults omitted corporate to true, so the corporate area-reference validation cannot succeed for this example.

Confirmed by source inspection on current main (2bb7c755692674ad619ffc46a0a17a781f019106) and a Configurator contract test. No cloud apply was performed. The existing Configurator's legacy Standalone editor explicitly writes corporate = false, hiding the template problem; a lossless importer must not silently reinterpret the source.

Evidence

• Standalone example
• Root corporate default and area-reference validation

Expected result / acceptance

• Mark the Standalone example project explicitly as Public (corporate = false) or otherwise resolve its missing connectivity consistently with the Standalone use case.
• Preserve the existing root default for other consumers unless a separately documented compatibility decision changes it.
• Add an offline/native contract test for this template with all required fixture identities, ensuring no corporate network reference is required.
• Regenerate affected template catalogues after accepting the source change; preserve previously saved Configurator revisions and export hashes.

Related: #20 established template test coverage, but is closed and does not document this specific mismatch.