This change detects the most recent git commit short hash and writes it to the `GIT_COMMIT_INFO` constant in `packages/cli/src/generated/git-commit.sh`, optionally appending the string "(local modifications)" if additional local changes after that commit are detected.
If set, this string is displayed in the `/about` dialog as well as passed into the `/bug` template.
Example:
```
> /about
╭───────────────────────────────────────────────────────────────────────────╮
│ │
│ About Gemini CLI │
│ │
│ CLI Version development │
│ Git Commit 43370ab (local modifications) │
│ Model gemini-2.5-pro-preview-05-06 │
│ Sandbox sandbox-exec (minimal) │
│ OS darwin v23.11.0 │
│ │
╰───────────────────────────────────────────────────────────────────────────╯
```
Additionally, this change updates `.gitignore` to ignore the generated files, `scripts/clean.sh` to remove them, and adds a `npm run generate` stage for this and any other generators we need to write.
