Add persistent terminal aliases

[cursor]

Issue

Problem

The terminal UI advertises an alias command, but the current implementation only prints a hard-coded example. That leaves a gap in the site's terminal-emulation goal: visitors cannot create shortcuts, inspect aliases, or remove them like they would in a real shell.

Proposed improvement

Add persistent, shell-style alias management to the browser terminal. Aliases should be stored client-side, expand before command execution, preserve additional arguments, work with supported pipelines, and include loop protection.

Acceptance criteria

• alias lists saved aliases and explains how to create one when none exist.
• alias name='command' creates or replaces an alias.
• alias name prints one alias or a not-found error.
• unalias name removes an alias; unalias -a clears all aliases.
• Alias names participate in tab completion and which reports alias definitions.
• Aliases persist across page reloads using localStorage.
• Recursive aliases are rejected with a clear loop error.

Changes

• Added alias parsing, formatting, normalization, and expansion helpers in src/lib/terminal/index.js.
• Wired persistent alias storage/execution into src/scripts/terminal.js, including pipeline aliases and which/tab-completion support.
• Added unalias to the command surface and help/man documentation.
• Documented alias usage in README.md.
• Added focused Vitest coverage for alias parsing, formatting, expansion, and loop detection.

Validation

• pnpm test -- tests/unit/terminal.test.js passed: 71 tests.
• Pre-push pnpm check passed: lint, format check, coverage, and Astro build.
• Manual browser walkthrough passed and was recorded: <video src="/opt/cursor/artifacts/persistent_terminal_aliases_walkthrough.mp4" controls></video>