fix(perf): build input.wasm with -O2 not -Oz

The opt-flags split defaulted input.wasm to -Oz (optimize for size),
which ~2x'd instruction counts on the hot parse paths (multi-byte UTF-8
decode, Kitty CSI-u trie). CodSpeed flagged UTF-8 3/4-byte and Kitty
regressions on PR #37. -O2 restores parse speed for +1557 bytes raw /
+290 bytes gzip on a 9KB module — a negligible size cost.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: natemoo-re

Makefile

@@ -5,7 +5,7 @@ CFLAGS_BASE = --target=wasm32 -nostdlib \
               -mbulk-memory \
               -Isrc -I.
 
-INPUT_OPT  ?= -Oz
+INPUT_OPT  ?= -O2
 LAYOUT_OPT ?= -O2
 
 LAYOUT_CFLAGS = $(CFLAGS_BASE) $(LAYOUT_OPT) -DCLAY_IMPLEMENTATION -DCLAY_WASM