refactor: restructure CLI commands and fix API response parsing

[pratik50]

Summary

Renamed stream to dataset across the PB CLI and fixed multiple API/response mismatches found during real testing with the current Parseable server, added new login methods and commands for pb.

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Key Changes

Rename: stream → dataset

• pb stream → pb dataset
• Updated CLI help text and internal type naming (Stream* → Dataset*)

refactor (feat): login command

• Used the username, password and Token based logi for self hosted.
• Implemented token and OAuth loing for Cloud server users.

Feature: added status command

• This will provide the server connection information, like current pb profile is connected to which server and status.
• eg. Profile name, connection url, connection status etc.

Feature: added logout command

• This command will erase the perticular profile from the config file along with all the its info.
• This command will not make the data to "" or NULL!! now this is written in way it will remove the whole profile from toml list.

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Fixes

Dataset stats

• Fixed size fields parsing (string → uint64)
• Improved HTTP error handling
• Proper handling of empty datasets (404 no longer crashes)

Query

• Switched to json.Marshal for request body generation (safer than raw string templating)

Roles

• Removed unused Tag field
• Fixed role list parsing (server returns a map, not an array)
• Fixed role details parsing (actions are wrapped under { "actions": [...] })

Users

• Updated user role response struct to correctly handle roles and group_roles

Tail

• Added reconnect loop so pb tail keeps streaming instead of stopping on disconnect
• Added helper to detect normal stream end vs real errors

Test

• Tested all the command on Staging and all are working as expected with all pass checks.