Add undici-based HTTP/HTTPS proxy support with tests and documentation

[rattalur]

This pull request adds support for running the CLI behind an HTTP or HTTPS proxy, configurable via standard environment variables. It introduces a new utility for proxy configuration, updates documentation to describe proxy usage, and adds direct support for proxying all API requests. The implementation ensures that proxy settings are respected consistently, including bypass logic via NO_PROXY, and is fully tested.

Proxy support implementation:

• Added a new utility (src/utils/proxy.ts) that resolves HTTP_PROXY/HTTPS_PROXY (case-insensitive), honors NO_PROXY for bypassing, and installs an undici.ProxyAgent as the global dispatcher for all outbound API requests.
• Updated the CLI entrypoint (src/index.ts) to call configureProxyFromEnv() before any API configuration or command registration, ensuring proxy settings are applied globally. [1] [2]

Dependencies and testing:

• Added undici as a direct dependency in package.json to provide the proxy agent and dispatcher.
• Added comprehensive unit tests for proxy resolution, bypass logic, and dispatcher installation in src/utils/proxy.test.ts.

Documentation updates:

• Documented proxy support and environment variables in README.md (new "Proxy Support" section), AGENTS.md (environment variable table), and SPECS/README.md (feature changelog). [1] [2] [3] [4]

Resolves Issue #40

[codacy-production]

Not up to standards ⛔

🔴 Issues 1 minor

Alerts:
⚠ 1 issue (≤ 0 issues of at least minor severity)

Results:
1 new issue

Category	Results
Comprehensibility	1 minor

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🟢 Metrics 40 complexity · 0 duplication

Metric	Results
Complexity	40
Duplication	0

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[codacy-production]

Pull Request Overview

The implementation correctly introduces proxy support using undici, and the project remains 'up to standards' according to Codacy. However, there is a logic flaw that should be addressed before merging: the current configuration only checks the NO_PROXY bypass for the primary Codacy API host during initialization.

Because the undici.ProxyAgent is not initialized with the noProxy configuration, all other outbound requests (such as fetching CVE data from Mitre) will be forced through the proxy even if they are explicitly listed in the environment variables. Leveraging the library's native bypass support will provide a more robust and standard-compliant implementation.

About this PR

• The implementation should aim for full parity with standard networking tools by ensuring all outbound requests—not just the primary API calls—respect the NO_PROXY configuration. Transitioning to the native noProxy option in undici will solve this systemically.

Test suggestions

• Verify resolveProxyUrl handles precedence (HTTPS > HTTP) and case-insensitivity correctly.
• Verify shouldBypassProxy handles exact matches, suffix matches, and the wildcard '*' correctly.
• Verify configureProxyFromEnv installs the global dispatcher with the resolved URL.
• Verify configureProxyFromEnv skips installation if the API host matches a NO_PROXY entry.
• Verify proxy bypass logic respects the custom hostname from CODACY_API_BASE_URL.

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