3c875276c9
Implemented full security remediation following Universal Security Pilot protocol: - W1: Enforced SecureProvider at router and engine boundaries to prevent bypasses. - W1: Implemented path-sensitive policy for MCP tools. - W2: Added SHA256 hash verification for SLM downloads (llamafile). - W3: Enhanced secret redaction for private keys (full body) and high-entropy strings. - W4: Fixed symlink-based filesystem sandbox escapes in paths and grep. - W4: Documented CLI agent trust boundaries. Also added 'agy' (Antigravity) as a subprocess CLI provider with plain-text JSON schema support.