fix(api): escape template data in the rendered deploy-azure.sh (bicep/arm) #964

Problem

internal/api/handler_federation.go (around lines 558-562 on main) renders the bicep/ARM deploy-azure.sh script with the raw template data. It does not pass the data through the shell escaping (shellEscapeData) that the other rendered scripts get. A value that passes input validation but contains shell syntax is therefore interpolated into the script verbatim.

Found by the independent review of #955. The reviewer's example: a contact email with a valid quoted local part containing $(id) is accepted, and the command runs on the machine of whoever downloads and runs deploy-azure.sh.

Impact

The person who supplies the value is the one who downloads and runs the script, so this is a self-targeted injection with a narrow blast radius. It is still a correctness and safety gap: the generated script should never execute data. #952 (escape flag values per output format) asked for the server side to be confirmed, and this path is the remaining gap.

Repro (no real Azure needed)

1. Request the bicep or ARM federation bundle with an email such as "a$(id)b"@example.com, or any field rendered into deploy-azure.sh that allows $(.
2. Inspect the rendered deploy-azure.sh. The value appears unquoted or unescaped inside a double-quoted shell context.
3. Run bash -n on the file to see that it parses, then run it in a sandbox with az stubbed: id executes.

Suggested fix

Render that template with shellEscapeData(data), as the other script paths do. Add a test that renders deploy-azure.sh with a $(...) payload and asserts the output contains no unescaped command substitution.