feat(qir): function SECURITY and SET search_path options (1–2h)

[flyingrobots]

Add SECURITY {INVOKER|DEFINER} and optional SET search_path to QIR emitFunction and expose via CLI as --ops-security/--ops-search-path.

Acceptance:

• emitFunction supports security+search_path
• CLI flags documented and passed to emission
• Snapshot tests for attributes
• Docs updated