[Pratt parser] Simplify helper methods and inlining

[dmitriplotnikov]

Summary

Simplifies pratt_parser.go by inlining single-callsite helper functions (initTokenStream, parse, newLogicManager, receiverCallOrMacro, globalCallOrMacro), while maintaining distinct branches for - and ! and preserving recursive descent stack frame sizes.

Recursion Depth Test (Stack: 64 KB)

Category	ANTLR (Max Depth OK)	Pratt (Max Depth OK)	Pratt Advantage
Parens ((((...42...))))	20	unlimited	unlimited
Unary (! ! ! ... true)	unlimited	unlimited	1.0x
Binary (1 + (1 + (...42...)))	21	93	~4.4x
List ([[[...42...]]])	18	85	~4.7x

Benchmark Results (Sequential & Parallel)

Benchmark Category	ns/op	B/op	allocs/op
Simple	27,429 ns/op	13,535 B/op	404 allocs/op
Complex	107,297 ns/op	51,864 B/op	1,397 allocs/op
Macros	50,519 ns/op	23,883 B/op	641 allocs/op
Errors	83,839 ns/op	37,764 B/op	1,176 allocs/op
Parallel/Simple	6,732 ns/op	13,494 B/op	404 allocs/op
Parallel/Complex	26,721 ns/op	51,865 B/op	1,397 allocs/op
Parallel/Macros	11,902 ns/op	23,732 B/op	641 allocs/op
Parallel/Errors	21,489 ns/op	37,659 B/op	1,176 allocs/op