Extract SqliteNumericText and collapse the duplicate numeric getters #200

Goal

Move SQLite text-to-number parsing out of LibsqlResultSet, and collapse the two duplicated getter ladders. getInt repeats toLong plus a cast, and getFloat repeats toDouble plus a cast.

Depends on

#199. Same file.

Pin

LibsqlResultSetTest covers non-numeric text, numeric prefixes, leading whitespace and trailing garbage, exponent rules, BLOB coercion, int64 wrapping, and float rounding. LibsqlResultSetGetBooleanTest covers the boolean route.

Scope

• Create SqliteNumericText with parseLong, parseDouble, and blobAsText from LibsqlResultSet 521 to 624.
• Move toLong and toDouble or keep them in the result set and delegate. Keep one definition of each.
• getInt becomes (int) toLong(getCurrentValue(columnIndex)).
• getFloat becomes (float) toDouble(getCurrentValue(columnIndex)).

Preserve

• Overflow saturates to Long.MIN_VALUE or Long.MAX_VALUE.
• Parsing takes a numeric prefix only. An exponent counts only when at least one digit follows it. Failure yields 0 or 0.0.
• The whitespace set is space, \t, \n, \r, vertical tab, form feed. Do not use Character.isWhitespace.
• getBoolean keeps routing through getInt, so a REAL 0.5 is false.

Acceptance

• SqliteNumericText.java exists, and each numeric getter is one delegation plus its cast.
• LibsqlResultSet.java is under 950 lines.
• ./mvnw -pl libsql-jdbc -am test green with no assertion edited.
• ./mvnw spotless:check green.