feat(debug): instruction-level coverage and FP register display

Assisted-by: GLM 5.3 Flash

CHANGELOG.md

@@ -23,6 +23,14 @@ Unreleased changes on the `development` branch.
 - **Conditional breakpoints.**  `break <label> if <reg> <op> <val>` now also
   compares two registers (`break loop if RAX > RBX`), not only a register
   against an immediate.
+- **Instruction-level coverage.**  `gasm debug --cover` now sets a
+  breakpoint on every instruction (walked by disassembly length), counts
+  the hits per instruction and reports the executed instructions with
+  their hit counts, with the label coverage derived from the same run.
+  Expect the run to slow to ptrace speed.
+- **FP register display on riscv64 and loong64.**  The debugger `regs`
+  command shows the 32 FP registers plus fcsr (and fcc on loong64) via
+  `PTRACE_GETREGSET`, where it previously printed nothing.
 - **JIT execution trampolines.**  `verify.Call` now works on all four
   architectures via hand-written assembly trampolines
   (`trampoline_{arm64,riscv64,loong64}.s`) that save the Go stack, switch