Centralize cross-frame DOM and drag handling so canvas interactions use a
single coordinate conversion and listener lifecycle.

- consolidate resize, spacing, block movement, panning, and insertion drags
- manage event forwarding and drop-zone cleanup per iframe registration
- remove obsolete outer overlay and unused frame document state
- preserve editable targets when forwarding iframe events
- fix HTML editor double-click and context-menu dispatch inside frames
- initialize fonts after teleported canvas elements are mounted
- keep iframe styles, classes, and theme attributes synchronized
- consolidate async client-script cleanup and error handling
- prevent history from remaining paused when insertion targets disappear
- remove leftover event and history debug logging

Verification:
- production frontend build passes
- touched iframe modules pass focused TypeScript checking
- browser and Cypress testing left for manual verification

Execute attached page-level JavaScript and CSS inside each rendered
breakpoint iframe.

- apply page CSS continuously in attachment order
- run page JavaScript through the existing restricted or unrestricted
  canvas sandbox
- expose iframe document, window, events, and page_data where allowed
- reuse the existing Run, Stop, and Refresh canvas controls
- recreate frames when scripts, page data, settings, or pages change
- preserve script ordering when loading page client scripts
- synchronize attached scripts after create, attach, update, rename,
  remove, and reorder operations
- keep the existing execute_block_scripts_in_editor field for
  compatibility while updating its label to cover all client scripts
- retain existing block and component script behavior