fix: add -R flag to less for LESS_TERMCAP color support

[TunaCuma]

Summary

Fixes #1

Adds the -R flag to all less invocations in zvm_open_less() to enable raw escape sequence passthrough.

Problem

Users who rely on LESS_TERMCAP_* environment variables for man page colors were not seeing colors when using this plugin. This is because:

1. The plugin sets MANPAGER=cat to capture raw man output
2. The output is piped to less without the -R flag
3. Without -R, less doesn't pass through ANSI escape sequences needed for color display

Solution

Add -R flag to all less calls, which tells less to interpret raw control characters. This enables:

• LESS_TERMCAP_* color variables to work correctly
• ANSI color codes from man pages to display properly

Changes

• lib/pager.zsh: Added -R flag to all ${ZVM_MAN_PAGER} invocations in zvm_open_less()