debt: use alias_generator=to_camel on Pydantic models

[RohithPariki]

Description

This PR cleans up the manual camelCase aliasing across our Pydantic models.

Instead of adding Field(alias="camelCaseName") everywhere, I've updated the ConfigDict on our models to use alias_generator=to_camel and populate_by_name=True. I then stripped out all the redundant alias= strings from the individual fields.

A few notes:

• I left specific internal overrides (like alias='__crawlee') untouched so we don't break any core logic.
• Ran ruff to clean up the formatting after removing the fields.

Issues

• Closes: Use alias_generator=to_camel on Pydantic models instead of manual per-field aliases #1954

Testing

• Verified locally that Pydantic models with alias_generator=to_camel and populate_by_name=True correctly map incoming camelCase JSON keys into snake_case Python attributes, perfectly mimicking the behavior of the removed manual aliases.