chore: release version 0.5.5

[TheStreamCode]

Summary

Prepares the audited Chutes Usage Monitor hardening work for the patch release 0.5.5.

Changes

• bump package.json and the npm-managed lockfile to 0.5.5
• synchronize CITATION.cff, release date, changelog, and README release summary
• improve Marketplace metadata for PAYG credit and read-only behavior
• clarify refresh behavior, in-memory snapshot handling, privacy, support, and documentation navigation
• keep runtime behavior and compatibility contracts unchanged from the already merged audit

Verification

• npm ci
• npm run preflight
• 83/83 tests pass with no skips
• full and runtime-only npm audits report zero vulnerabilities
• Gitleaks reports no leaks
• local documentation links resolve
• VSIX manifest and package metadata both state 0.5.5
• VSIX contains 32 expected files and excludes sources, tests, maps, secrets, and GitHub-only assets
• VSIX SHA-256: C32F1356A0AC3B45069497340AA475DC2F607B2BD123409A036277015C62A6C1

Release

After merge, the maintainer will create tag v0.5.5 and a GitHub Release with chutes-usage-vscode-0.5.5.vsix.

Marketplace and Open VSX upload remain owner-managed and are not performed by this PR.