fix(asm): encode RISC-V CALL sym(SB) as JAL

Assisted-by: DeepSeek V4 Pro

CHANGELOG.md

@@ -82,6 +82,14 @@ Unreleased changes on the `development` branch.
   encoders were removed, and the `C.LUI` direct-instruction compression now
   uses the correct six-bit signed range.  A byte-exact ground-truth test
   covers the branch family and jumps against `GOARCH=riscv64 go tool asm`.
+- **RISC-V `CALL sym(SB)`.**  The call pseudo-instruction now emits the
+  toolchain's `JAL X1, sym(SB)` with a single `R_RISCV_JAL` relocation
+  (previously it emitted an `AUIPC`+`JALR` pair against a local branch
+  label, a form `go tool asm` rejects).  The GOOBJ and ELF emitters now map
+  that relocation (Go objabi 59 / ELF `R_RISCV_JAL` 17, a 4-byte field), and
+  relocation offsets are recorded relative to the function start (including
+  the prologue).  A byte-exact ground-truth test covers a call against
+  `GOARCH=riscv64 go tool asm`.
 - **Debugger watchpoint slots.**  `gasm debug`'s `watch` command always used
   hardware watchpoint slot 0, so a second `watch` call silently overwrote
   the first.  Watchpoint slots are now tracked in the `Session` (DR0–DR3);