fix: can't combine Shift and Down #641

[security-log]

Fixes #641

Changes

Modified: command.go
Keep the Shift modifier held while typing navigation keys so Shift+Arrow/Page/Home/End fire the correct rod key codes.

Modified: parser/parser.go
Allow Shift commands to consume navigation tokens (Arrow, Page, Home, End) in addition to the existing literals.

Modified: parser/parser_test.go
Add coverage for parsing Shift+Down and Shift+Tab.

Modified: record.go
Map Shift+Arrow escape sequences, sort substitutions by length to avoid partial matches, and preserve Shift-prefixed commands during sanitization.

Modified: record_test.go
Verify that the recorder now turns Shift+Arrow escape sequences into Shift+… commands.

Why

Shifted navigation keys were emitted as plain text (Down, Up) or broken into Escape fragments, so we couldn’t replay selections made with Shift while recording or parsing tapes. These changes teach the recorder, parser, and executor to treat shifted navigation as first-class commands.

How to reproduce

Before the fix

go test ./record -run TestInputToTape/Shift+Arrow -count=1
--- FAIL: TestInputToTape (0.00s)
    record_test.go:...: want:
    Shift+Down
    ...
    got:
    Escape
    [1;2B
    ...

After the fix

go test ./record -run TestInputToTape/Shift+Arrow -count=1
ok   github.com/charmbracelet/vhs/record