fix: accept no-browser wallet flows

[brendanjryan]

Summary

• Change login and fund browser options to use incur's positive boolean option shape
• Preserve --no-browser behavior via boolean negation parsing
• Add parser regression coverage for login and fund no-browser flows

Motivation

incur treats --no-* flags as boolean negation. Defining a literal no-browser option caused tempo wallet login --no-browser to fail with an unknown flag even though the command help and docs referenced that flow.

Key design considerations

• Uses browser: true as the schema default so --no-browser parses to browser: false
• Applies the same fix to fund, which used the same option shape
• Keeps help text explicit that --no-browser disables browser opening