Add store list for organization stores

[dmerand]

Summary

Add shopify store list, listing the stores in the Shopify organizations available to the current CLI account.

Builds store list out from the prototype in the shopify store create preview stack.

Scope

• add shopify store list (organization source, backed by Business Platform internally)
• discover organizations and list per-organization stores, keeping successful organizations with a warning when some fail
• render Subdomain | Name | Type | Created, sorted newest first
• cap the listing at 250 (newest first); on truncation, emit a stderr warning and a truncatedFrom count in JSON
• add optional --organization-id to list a single organization; an unknown/inaccessible id errors with the organizations you can access
• model retrieval as a discriminated success | unresolved-session | organization-not-found result so fallback policy can live in the service index
• harden the CLI session read against malformed persisted JSON

Review notes

• user-facing output and the command contract avoid the internal "Business Platform" naming; the command is framed around your Shopify organization
• the --from flag, the store-auth source, and the auto fallback land in Add store-auth source and auto fallback to store list #7714

[dmerand]

• Add store-auth source and auto fallback to store list #7714
• Introduce local store auth summary API #7709
• Add store list for organization stores #7708 👈 (View in Graphite)
• main

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