perf: small inflates start small and skip unread tables

[Chimi6]

• One-shot inflate of a small input starts from a slab of 4x the input (at least 4 KB) and doubles, instead of a zeroed megabyte per call (a map, its faults, and an unmap).
• The packed literal table is built only for one-shot inputs of 4 KB and up (and always for streaming inflaters); packed copies of the distance and code-length tables are no longer built (only the literal table's is read); the long-code scratch table is skipped when no code passes 12 bits.
• A 300-page PDF whose pages are 14,400 small content streams: 0.61 -> 0.13 s, output identical. xlsx -> csv 1891 -> 1830 ms, pdf -> png 386 -> 367 ms; docx -> md 1753 -> 1813 (the same streaming inflater; recorded as layout, margin 75x over pandoc).
• Test: a small input inflating far past its first slab, and a small dynamic block without the packed table.