[FR]: Wait for manual input before rebuild with aspect-watch

### What is the current behavior?

When a change is detected during a watch, we immediately analyze the changes and start a rebuild if necessary. If there is any debouncing, it is relatively small compared to the time it takes to build or edit code.

### Describe the feature

Using watch is great when making small changes to a small number of files at once. But with long build times especially, I find myself wanting to keep changes in the buffer longer, across files, before saving just prevent a rebuild from starting prematurely.

This sort of works when manually editing, but not while an LLM is editing files. I want to request a way to still watch files, but require a manual key press/input before doing a full pass of detecting changes + rebuild. That way we can only start the rebuild when the LLM is done without needing to kill and restart the whole process. Plus it'll be a bit nicer to use when making manual edits too.

Start at the aspect-watch watch loop and trace how file changes lead to analysis and rebuilding. Determine how manual input can defer that pass, then verify that edits accumulate without rebuilding until input triggers the normal detection and rebuild flow. Add or update watch behavior tests if an existing test location is found.

Written by the indexing model from the issue text.