Fix shell interpolation that corrupts the model pricing summary

[atimics]

Evidence

deprecated-claude-app/backend/config/setup-config.sh:51-54 prints dollar-denominated prices inside double-quoted strings. Bash interprets values such as $15, $75, $10, and $30 as positional-parameter expansions rather than literal currency.

ShellCheck reports SC1037 on these lines.

Reproduction

shellcheck -S warning deprecated-claude-app/backend/config/setup-config.sh
bash deprecated-claude-app/backend/config/setup-config.sh

The second command should only be used with dummy inputs because the script writes configuration.

Acceptance criteria

• Quote or escape all currency values so the displayed summary is literal and deterministic.
• Add a non-mutating test for the generated output.
• Make ShellCheck pass for this script.
• If this deprecated application is intentionally unsupported, remove the executable setup path instead of leaving a broken operator command.