feat: add version pinning support to install.sh

[Copilot]

The install script only supported installing the latest version. Users need to pin specific versions for reproducibility and rollback scenarios.

Changes

• Version selection priority: argument > AWF_VERSION env var > fetch latest
• Version validation: strict semver format vX.Y.Z with anchored regex
• Updated docs: script header and README with usage examples

Usage

# Install specific version via argument
curl -sSL .../install.sh | sudo bash -s -- v1.0.0

# Or via environment variable
curl -sSL .../install.sh | sudo AWF_VERSION=v1.0.0 bash

# Default: latest (unchanged behavior)
curl -sSL .../install.sh | sudo bash

Original prompt

install.sh should be able to pass in a version to pin the version (default uses the latest

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[github-actions]

Test Coverage Report

Metric	Coverage	Covered/Total
Lines	66.1%	708/1071
Statements	66.27%	729/1100
Functions	70.73%	87/123
Branches	60.89%	232/381

Coverage Thresholds

The project has the following coverage thresholds configured:

• Lines: 38%
• Statements: 38%
• Functions: 35%
• Branches: 30%

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Coverage report generated by `npm run test:coverage`