synth v0.63.0

What's Changed

• plan(v0.63): breadth AND depth — 8 → 10 artifacts, x86 and SIMD decided rather than drifting by @avrabe in #1162
• chore(varve): pin the toolchain layer — loom 0.1.0 vs 1.2.0 and meld 0.9.0 vs 0.42.0 measured on PATH by @avrabe in #1163
• RQ-63-ARMI64OFF: ARM load/store static offsets past the immediate field — materialize on A32 (never mask), un-clamp Thumb-2 i64; oracle landed red-first by @avrabe in #1165
• RQ-63-A64STACK: aarch64 — values below a call's args survive the call (spill/reload), oracle-first by @avrabe in #1164
• RQ-63-LADDER: acceptance-ladder harness as a mode of the existing census (rungs separate, NEVER attributed) by @avrabe in #1169
• feat(riscv): RQ-63-RVGLOBAL — RV32 lowers global.get/global.set via a synth-emitted .data region, full-boot oracle red-first by @avrabe in #1166
• RQ-63-WASTCLOSURE (#1168): the .wast path applies the reachable-callgraph closure, and a relocation against an unplaced function is refused whatever the reason by @avrabe in #1170
• RQ-63-FLOOREQ (#910): enforce the floor EQUALITY invariant — the rule v0.62 wrote down and did not install by @avrabe in #1172
• RQ-63-LADDER + RQ-63-SPECFAM published, RQ-63-ACKDEFAULT decided — the three must artifacts close by @avrabe in #1173
• chore(rivet): record WHY four v0.63 artifacts are deferred — scope decision, surfaced not silent by @avrabe in #1174
• release(v0.63.0): "Raise the percentage, and say which percentage" — 12 artifacts, 8 implemented by @avrabe in #1175
• chore(release): fill v0.63's step-8 attestation with the measured result (0-line diff) by @avrabe in #1176

Full Changelog: v0.62.0...v0.63.0