Add versioned CLI help and update command

[PabloZaiden]

Summary

• Added CLI version metadata and included it in help output.
• Implemented the update action with supporting update logic.
• Documented the new update command usage in the README.
• Added tests covering CLI help behavior and update command flows.

Changes

• Introduced src/version.ts for shared version handling.
• Added src/server/update.ts and comprehensive update tests.
• Wired the update command into CLI command handling and TypeScript configuration.

[Copilot]

Pull request overview

This PR adds version metadata to the CLI help output and introduces a new link-cli update command that can check for and install newer GitHub release binaries, along with documentation and tests to cover the new behavior.

Changes:

• Added shared version helpers (LINK_VERSION, formatLinkVersion) and surfaced version info in top-level CLI help.
• Implemented a GitHub-release-based self-update flow (update command) with platform/asset resolution and error handling.
• Added/updated tests and README docs for the new help/version output and update workflows.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tsconfig.json	Enables JSON imports to support reading version metadata from package.json.
src/version.ts	Introduces shared version constant + formatting used in help output.
src/server/update.ts	Adds the self-update implementation (release lookup + asset download + binary replacement).
src/server/update.test.ts	Adds tests for version parsing/comparison and update flows.
src/server/commands.ts	Wires the new update command into CLI command execution and passes current version.
src/server/cli.ts	Adds parsing/help text for the new update command and prints version in top-level help.
src/server/cli.test.ts	Adds tests asserting version in help output and update parsing behavior.
src/index.ts	Awaits async CLI command runner to support async update logic.
README.md	Documents the new update command usage and notes installed-binary requirement.

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