SuperCan original-numeric Vorbis decoder

This is a privately named, decoder-only modification of Xiph.Org libvorbis
1.3.7, pinned to upstream commit
0657aee69dec8508a0011f47f3b69d7538e9d262. The BSD-style copyright, conditions
and disclaimer are reproduced in COPYING. Per-file copyright notices remain
in the source. Reproduce these terms in binary distribution materials.

Candidate numerical ancestry was investigated at upstream commit
49cf037a31776890ca95e65f36144fae2b357f46; its BSD-style copyright, conditions
and disclaimer are reproduced in COPYING.candidate. This candidate is not
asserted to be the exact Vorbis version embedded in the original FMOD binary.
No proprietary FMOD or Microsoft CRT implementation is included here.

Local changes remove encoder-only implementations and declarations, privately
prefix all decoder-global symbols, retain the modern header/setup/transport
security checks and real half-rate decoder, and translate observed original
numerical operation/store order for dequantization, MDCT coefficients and
inverse transform, synthesis windows, and overlap-add. The application-facing
AudioClip/decode_audio interface and WAVE decoding are unchanged. Public
system libogg provides packet/stream transport; system libc/libm provide the
ordinary C runtime/math ABI. No system Vorbis symbol is interposed, and no
original DLL or Wine component is a production dependency.

The observed numerical reference is an unchanged original-library software
path captured privately with nearest-rounding PC53 x87 control and MXCSR
1f80. This does not establish the original Windows game's floating-point
state, selected device/backend, audibility, or general waveform parity.
The actual two reference Vorbis assets select floor1. The retained modern
floor0/LSP implementation is functional but its original FLOAT_LOOKUP
numerical parity is not established. Modern packed-float exponent safety
clamping remains; it is inactive for every mapped book in those two assets.

Upstream byte/blob/SHA256 provenance and local numerical evidence are recorded
in analysis/ghidra/privateaudio-vorbis-upstream/sources-manifest.json and
analysis/ghidra/privateaudio-vorbis-synthesis-evidence/. Neither the original
binaries nor privately owned asset contents are redistributed by this fork.
