Summary

• Add CompiledTickExpression that pre-parses tick expressions containing date variables ($now, $today, $yesterday, $tomorrow) into a single long[] IR at compile time. Runtime evaluate() performs only long arithmetic — no string parsing, no allocations.
• Add DateVariableExpr to encode/evaluate $variable ± offset expressions (supports all time units plus business days).
• Add IntervalUtils.compileTickExpr() that builds the IR: duration parts, time override triples, and element entries (SINGLE_VAR, STATIC, RANGE) packed into one array with a header.
• Wire through RuntimeIntervalModelBuilder: expressions containing $ variables now produce a dynamic CompiledTickExpression instead of re-parsing the string on every query execution.
• Replace Character.isWhitespace / Character.isDigit with Chars.isAsciiWhitespace / Chars.isAsciiDigit throughout IntervalUtils to avoid locale-dependent behavior.

IR design

ir[0]           header (elem/timeOverride/duration counts, dayFilterMask, flags)
ir[1]           numericTzOffset (Long.MIN_VALUE if named tz)
ir[2..2+D)      duration parts (unit + value per long)
ir[2+D..2+D+3T) time override triples (offset, width, zoneMatch)
ir[2+D+3T..end) elements: TAG_SINGLE_VAR(1 long), TAG_STATIC(3 longs), TAG_RANGE(2 longs)

Non-encodable fields (TimeZoneRules, DateLocale, LongList exchangeSchedule) remain as object references on the CompiledTickExpression instance.

Evaluate algorithm

1. Walk elements → emit intervals (single var, static pass-through, or day-by-day range iteration)
2. Apply day filter bitmask (local time)
3. Apply timezone (numeric subtraction or DST-aware toUTC)
4. Apply exchange schedule filter + optional duration
5. Sort and merge overlapping intervals

Test plan

• Oracle tests (assertCompiledTickExpr) compare compiled evaluate() vs reference parseTickExpr with 10 random "now" values per expression
• Fixed-now tests (assertCompiledTickExprWithNow) for DST edge cases (spring forward, fall back, per-element + global named timezone)
• Negative tests (assertCompileTickExprError) for invalid expressions
• Coverage for IR growth (bracket expansion filling initial 64-long array)
• Edge case tests for mixed-precision ranges, month-precision static with day filter, sub-day ranges spanning midnight, $now with timezone, mixed $now/$today lists with time override
• DateVariableExpr unit tests for all variable types, offsets, business days, case insensitivity