feat(asm): emit RISC-V GOOBJ with the shared emitter

Assisted-by: DeepSeek V4 Pro

CHANGELOG.md

@@ -26,6 +26,14 @@ Unreleased changes on the `development` branch.
   in the architecture's MinLC units as the runtime expects — the amd64 link
   test now genuinely substitutes the gasm object, and the amd64/loong64
   end-to-end GOOBJ link tests pass.
+- **RISC-V GOOBJ emission via the shared emitter.**  RISC-V GOOBJ output is
+  now written by the same shared emitter as amd64 and LoongArch, modelling
+  each AUIPC + second-instruction pair as a single R_RISCV_PCREL_ITYPE/STYPE
+  relocation (the layout `cmd/asm` writes, not the ELF HI20/LO12 pair), so the
+  object links into a cross-compiled `go build` for `GOARCH=riscv64`.  An
+  end-to-end link test substitutes the gasm object and reads the symbol back
+  with `go tool nm`; the rewrite also corrects the relocation `after` field
+  and the compressed `RET` encoding (C.JR ra).
 
 ### Fixed