[Enhancement] Implement Aliases (alias ll='ls -lah')

[aphexlog]

Allow users to create command shortcuts using alias.

Tasks:

• Parse alias NAME=VALUE.
• Store aliases in-memory.
• Expand aliases before executing commands.

Acceptance Criteria:

• alias ll='ls -lah' stores the alias.
• Running ll executes ls -lah.
• Running alias lists all defined aliases.