the jetbrains overlay binds `ctrl-alt-l` (linux) / `cmd-alt-l` (macos)
to `editor::Format` (jetbrains "reformat code"), which collides with the
default `agent::OpenRulesLibrary` binding. the agent panel shows the
conflicting key as the rules tooltip but pressing it formats the buffer
instead of opening rules. mirrors the windows keymap by switching the
linux/macos overlays to `shift-alt-l` in the AgentPanel context (with
the colliding key explicitly null-ed), so the hint and the action stay
in sync.

closes #49764.

Release Notes:

- Fixed the JetBrains keymap so the agent panel "Rules" entry uses
`shift-alt-l` and no longer flickers a non-functional `ctrl-alt-l` /
`cmd-alt-l` shortcut.