Add a fancy debug page

Rough idea:

* Save html page for each spec to `tmp/lucky_flow/debug_pages/`. Example: `tmp/lucky_flow/debug_pages/signs-a-user-in-spec.html`
* Show what interactions happened (Ran `click "@heading"`, Ran `fill UserForm`, etc.) on a pane to the left
* Clicking what happened in the left plane (`click "@heading"`) shows screenshot of the page on the right
* Would *love* to also include styles and images, but since the server stops after spec ends it could be really hard
* Maybe copy assets and rewrite the asset URLs the page? Probably too much for v1
* Also allow frameworks to extend the page and show other debug info
* What page was rendered
* What action rendered it
* What assigns were passed to it
* forms - so you can see forms
* context
* headers, etc.
* session
* Allow customizing objects `TheObjext#lucky_flow_inspect`
* So for forms you might show how if there are errors in an easily digestible way
* Or queries might show the SQL that it had and the results

## Examples of left pane

* Click `“@heading”` with text `“adds”`
* Fill `UserForm`
* Should have `“@heading”` with text `“adds”`

## Example of right pane

### Click `"@heading"` with text `"adds"`

### Details

* On page `Users::IndexPage`
* Data:
* Users: which would print the SQL that was run, number of results, etc.
* Rendered by `Users::Index`
* Params
* Headers

No source files, tests, or entry points are named. Start by tracing how specs and browser interactions are recorded, then define the first version around writing HTML under tmp/lucky_flow/debug_pages/ with an interaction pane and corresponding page screenshots; asset copying and framework extensions are explicitly broader follow-up ideas.

Written by the indexing model from the issue text.