Reject query and fragment components in custom base URLs

[rrajpuro]

Problem

Custom base URLs supplied through --base-url or DEFINED_BASE_URL currently accept query strings and fragments. _request then appends the endpoint directly to the configured value, producing malformed request targets.

For example:

https://proxy.example/api?token=x

combined with /v1/hosts becomes:

https://proxy.example/api?token=x/v1/hosts

The request therefore targets /api instead of /api/v1/hosts.

Proposed fix

Reject base URLs that contain query or fragment components during validation, or construct request URLs structurally so endpoint paths are composed correctly.

Acceptance criteria

• --base-url rejects values containing a query component.
• --base-url rejects values containing a fragment component.
• DEFINED_BASE_URL follows the same validation rules.
• Tests cover query and fragment inputs.
• Existing valid base URLs, including those with path prefixes, continue to work.

Affected code

src/defined_client/cli/core.py (base URL validation around lines 147–150).