Improve: Safer & faster case-folding on Ice Lake

Testing across different Leipzig dataset
languages yeilds the following results:

Tier 1: Excellent (5-7x speedup)
 Language      Script      Speedup  Notes
--------------------------------------------------------------------
 Hindi (hi)    Devanagari  7.10x    Pure 3-byte E0, no case folding
 English (en)  Latin       6.94x    Pure ASCII fast path
 Bengali (bn)  Bengali     6.49x    Pure 3-byte E0, no case folding
 Tamil (ta)    Tamil       6.41x    Pure 3-byte E0, no case folding
 Korean (ko)   Hangul      6.13x    Pure 3-byte EA, no case folding
 Dutch (nl)    Latin       5.31x    Mostly ASCII with some Latin-1

Tier 2: Good (3-5x speedup)
 Language         Script          Speedup  Notes
------------------------------------------------------------------------
 German (de)      Latin           4.38x    Latin-1 umlauts (ä, ö, ü)
 Portuguese (pt)  Latin           4.17x    Latin-1 accents
 Japanese (ja)    CJK + Hiragana  4.03x    Mixed but mostly safe 3-byte
 Ukrainian (uk)   Cyrillic        3.90x    Cyrillic fast path
 Spanish (es)     Latin           3.89x    Latin-1 accents
 Russian (ru)     Cyrillic        3.62x    Cyrillic fast path
 Greek (el)       Greek           3.44x    2-byte with +0x20 folding
 Hebrew (he)      Hebrew          3.35x    RTL script, no case folding
 Arabic (ar)      Arabic          3.35x    RTL script, no case folding

Tier 3: Moderate (2-3x speedup)
 Language       Script    Speedup  Notes
-------------------------------------------------------------------
 French (fr)    Latin     3.21x    Latin-1 + Latin Extended
 Armenian (hy)  Armenian  2.92x    2-byte with complex folding
 Persian (fa)   Arabic    2.91x    No case folding, mostly safe
 Czech (cs)     Latin     2.05x    Latin Extended-A (háčky, čárky)
 Polish (pl)    Latin     2.04x    Latin Extended-A (ł, ś, ź)
 Turkish (tr)   Latin     2.00x    Latin Extended (İ→i, dotless ı)

Tier 4: Limited (~1-2x speedup)
 Language         Script         Speedup  Notes
--------------------------------------------------------------------
 Chinese (zh)     CJK            1.89x    Has fullwidth A-Z (EF)
 Vietnamese (vi)  Latin Ext Add  1.04x    Mixed ASCII + 2-byte + E1

Tier 5: Regression (<1x)
 Language       Script    Speedup  Notes
--------------------------------------------------------------
 Georgian (ka)  Georgian  0.36x    Cross-block folding: E1→E2

Author: ashvardanian

CMakeLists.txt

@@ -435,6 +435,7 @@ if (STRINGZILLA_BUILD_BENCHMARK)
     define_launcher(stringzilla_bench_find_cpp20 scripts/bench_find.cpp 20 "${STRINGZILLA_TARGET_ARCH}")
     define_launcher(stringzilla_bench_sequence_cpp20 scripts/bench_sequence.cpp 20 "${STRINGZILLA_TARGET_ARCH}")
     define_launcher(stringzilla_bench_token_cpp20 scripts/bench_token.cpp 20 "${STRINGZILLA_TARGET_ARCH}")
+    define_launcher(stringzilla_bench_unicode_cpp20 scripts/bench_unicode.cpp 20 "${STRINGZILLA_TARGET_ARCH}")
     define_launcher(stringzilla_bench_container_cpp20 scripts/bench_container.cpp 20 "${STRINGZILLA_TARGET_ARCH}")
     define_launcher(stringzilla_bench_memory_cpp20 scripts/bench_memory.cpp 20 "${STRINGZILLA_TARGET_ARCH}")