v1.6.0

Added: identity package (User-Agent rotation)

• New package identity: CheckUserAgent and CheckUserAgents (1 to 256 printable ASCII characters, no line break, no leading or trailing space; at most 200 values, none twice), CheckKey, CanonicalHost, and SelectIndex / SelectUserAgent, the rule that picks one value of a rotation list per (scan run key, target host).
• The choice is sticky (every request of a run to a host carries the same value, whatever the port, scheme or case) and spreads runs and hosts evenly (HMAC-SHA-256 keyed by the run key over a fixed label and the canonical host). The rule is versioned by its label; a test pins its output.
• Additive: no existing package changes.