Fix panic when .netrc entry has no password

[aviu16]

Summary

Fixes a panic in get_credentials_from_netrc when a .netrc entry exists but has no password field.

Bug Description

In crates/aim-downloader/src/address.rs, the get_credentials_from_netrc function unconditionally unwraps machine.password:

if server == name {
    user.clone_from(&machine.login);
    pass = machine.password.clone().unwrap();  // Panics if password is None!
    break;
}

Crash Scenario

A .netrc file like this will cause a panic:

machine example.com
login myuser

When tabby tries to download from example.com, it finds the matching host in .netrc, but machine.password is None because no password was specified. The .unwrap() then panics.

Root Cause

The netrc crate's Machine struct has password: Option<String>, but the code assumes it's always Some.

Fix

Changed to use if let to only update the password if it exists:

if server == name {
    user.clone_from(&machine.login);
    if let Some(password) = &machine.password {
        pass = password.clone();
    }
    break;
}

If no password is in .netrc, the function now falls back to the password parameter (default: "anonymous").

Impact

• Prevents panic when .netrc entries have login but no password
• Maintains existing behavior: password parameter is used as fallback
• Matches how login is handled (which doesn't unwrap since it's not Option<String>)

Testing

The fix allows .netrc files with password-less entries to work without crashing. The existing test cases continue to pass.

🤖 Generated with Claude Code

[aviu16]

gonna close this one, realized i dont have bandwidth to follow up on review feedback rn. sorry about that!