sqlite: optimize column name creation and text value encoding

[thisalihassan]

Skip the full UTF-8 decode path for text values that are pure ASCII by validating with simdutf and creating OneByte V8 strings, halving memory.Internalize column name strings so V8 shares hidden classes across row objects. Cache column names in the iterate() hot loop, invalidating on schema changes via SQLITE_STMTSTATUS_REPREPARE.

Benchmark: 30-run

Refs: nodejs/performance#181

[nodejs-github-bot]

Review requested:

• @nodejs/sqlite

[thisalihassan]

I didn't push the changes for sqlite-prepare-select-all-options and sqlite-prepare-select-all where I tested the iterate method because it slows down the benchmark by a lot.
Adding iterate nearly ~2.3x the total benchmark runtime from ~40 minutes to ~90 minutes, but if needed I can push that as well
Benchmark with iterate: 30 runs

[codecov]

Codecov Report

❌ Patch coverage is 82.92683% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.77%. Comparing base (da5efc4) to head (4fcb1ed).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_sqlite.cc	82.92%	4 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61954      +/-   ##
==========================================
+ Coverage   88.84%   89.77%   +0.93%     
==========================================
  Files         674      674              
  Lines      204957   205638     +681     
  Branches    39309    39415     +106     
==========================================
+ Hits       182087   184605    +2518     
+ Misses      15088    13273    -1815     
+ Partials     7782     7760      -22     

Files with missing lines	Coverage Δ
src/node_sqlite.h	81.48% <ø> (+1.08%)	⬆️
src/node_sqlite.cc	80.91% <82.92%> (+0.01%)	⬆️

... and 179 files with indirect coverage changes

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