feat(security): harden mcp and action surfaces

[JSONbored]

Summary

• Upgrades Nightward’s MCP, action, Raycast, provider, TUI, release, and docs surfaces so users can actually take bounded actions instead of being pushed back to raw CLI commands.
• Adds the Codex Security hardening pass for action writes, MCP inputs/paths, Raycast provider installs, backup snapshots, and npm archive extraction.

What changed

• Added a shared Nightward action registry for disclosure, provider install/enable/disable, online-provider settings, schedule install/remove, backup snapshots, report/cache cleanup, and policy init/ignore-with-reason.
• Expanded the MCP server into a schema-backed product surface with tools/resources/prompts, structured output, tool annotations, direct action apply, strict input validation, and scoped path checks.
• Reworked Raycast and TUI action surfaces to preview/apply bounded registry actions with explicit confirmation.
• Added Grype, Syft, and OpenSSF Scorecard provider support plus provider fixtures and mocked provider contract coverage.
• Hardened state, audit, schedule, snapshot, and policy writes against symlinked Nightward-owned paths.
• Hardened the npm launcher with archive-entry validation and optional strict Sigstore verification.
• Replaced custom smoke/doc scripts with Vitest-backed suites for npm, Raycast, and site/docs contracts.
• Updated MCP/Raycast/privacy/testing/threat-model/release docs and support matrix.

Why

• The TUI, Raycast, and MCP surfaces were too informational and too easy to drift from CLI behavior.
• Write-capable behavior needed one security boundary: disclosure acceptance, preview, confirmation, availability checks, redacted output, and audit logging.
• The Codex Security pass found concrete pre-release hardening issues that needed fixes before calling this release secure.

Validation

• make verify
• make test-security
• make fuzz-check skipped because cargo-fuzz is not installed
• git diff --check
• Final grep audit for direct shell provider install bypasses and stale release/security docs claims

Notes

• Windows schedule install remains preview/fallback only.
• Windows ARM64 remains deferred.
• Live MCP/agent config mutation remains out of MCP v1 scope until preview, backup, rollback, and schema-specific tests exist.
• Security scan artifacts were kept outside product docs under /tmp/codex-security-scans/nightward-2026-05-06/.