Performance improvements

[mallport]

Step	Change	Pseudonymize avg	Delta vs previous	Delta vs original
1	Per-request crypto/function re-init optimization	101 ms	-6 ms	-6 ms
2	Field-match cache + metadata dedup (hot path)	93.1 ms	-7.9 ms	-13.9 ms
3	New fast endpoint (/pseudonymize/field-fast) initial	89.12 ms	-3.98 ms	-17.88 ms
4	Fast-path loop tuning (less stream/optional overhead)	81.49 ms	-7.63 ms	-25.51 ms
5	Minimal-metrics mode added (measurement split)	90.75 ms full / 64.81 ms minimal	n/a*	n/a*
6	Logging-path optimization (debug instead of info in hot path, cap collected logs)	80.99 ms full / 63.17 ms minimal	-9.76 ms (full vs step 5 full)	-26.01 ms (full)

---

This change is