Add make install and improve installation docs

[justincampbell]

Summary

• Add make install target that delegates to go install ./cmd/pomodoro
• Update README with make install option for local development
• Follows standard Go CLI project conventions for installation

Test plan

• Verify make install works locally
• Confirm installation docs are clear and accurate
• Test that installed binary works correctly

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

This PR adds a convenient make install target for local development and updates the installation documentation to include this new option. The changes follow standard Go CLI project conventions by providing a simple way to install the binary from a cloned repository.

• Add make install target that delegates to go install ./cmd/pomodoro
• Update README with installation instructions for the new make target

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
Makefile	Adds new install target for installing the binary locally
README.md	Updates installation documentation to include the new make install option

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[justincampbell]

Updated PR to fix version info for go install builds. Please re-review the changes.

[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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