Add a bunch of manually tested prompt changes that make Gemini 2.5 Pro work better for me

[nathansobo]

@osyvokon Could you take a look at formatting some of these, I pinged you in some feedback on recent threads in development mode and also did a thumbs up on a version with these changes. I'd appreciate your help getting these changes properly evaluated and dialed in, but they made a difference in my experience.

Closes #ISSUE

Release Notes:

• N/A or Added/Fixed/Improved ...

[osyvokon]

Edit evals look good:

 
 edit_file eval                         | `main`          | `tune_for_gemini`
----------------------------------------|-----------------|-------------------
 add_overwrite_test                     | 35%             | 40%
 create_empty_file                      | 100%            | 100%
 delete_run_git_blame                   | 100%            | 100%
 disable_cursor_blinking                | 100%            | 100%
 extract_handle_command_output          | 86%             | 98%
 from_pixels_constructor                | 94%             | 85%
 translate_doc_comments                 | 100%            | 100%
 use_wasi_sdk_in_compile_parser_to_wasm | 99%             | 97%
 zode                                   | 100%            | 100%
----------------------------------------|-----------------|-------------------
 *AVERAGE*                              | 90%             | 91%

I'll take a look what's wrong with from_pixels_constructor