docs: clarify report reload flow and remove dead keyboard-shortcut module

The power-bi-report skill claimed `pbi report reload` "sends a keyboard
shortcut" to Power BI Desktop. It does not. The actual implementation calls
sync_desktop(), which closes Desktop with save, re-applies PBIR edits the
save would overwrite, and reopens the .pbip. Users who looked up the
keyboard shortcut in Microsoft's docs (#8) found nothing and reported it
as broken.

Fix the skill text to describe what reload actually does, and add an
explicit note in the auto-sync section that sync closes-and-reopens
Desktop after each write so the behavior of `visual update` (and other
write commands) is no longer surprising. --no-sync remains the escape
hatch.

Also remove src/pbi_cli/utils/desktop_reload.py: dead code, no importers
in src/, only referenced by a stale lint exception in pyproject.toml.
The [reload] extras stays put because desktop_sync.py still needs pywin32.

Bump 3.11.1 -> 3.11.2.

Closes #8

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>