Adds `snapshot [FILE]` and `set speed|output|verify ...`/`info config`
(Req 5 AC 22 "Snapshots"/"Simulation parameters") to the interactive
simulation REPL.
`snapshot` reuses sim_record.c's existing sim_record_write_header_and_
snapshot() (task 11.5) rather than reimplementing capnp encoding, so
the produced file is genuinely loadable via a fresh --sim invocation
-- the task's own Observable. `set speed`/`set output`/`set verify`
mutate fields sim_loop.c and core_clock.c already read fresh on every
event/session, so no new hook points were needed and sim_loop.c stays
untouched at exactly 800/800 lines (this project's hard per-file cap).
New repl_params.c is a fourth sibling in the repl.c/repl_break.c/
repl_info.c split (task 12.2's precedent) -- neither existing file had
headroom left under the 800-line cap for this task's own logic.
Scheduler suite: 36/36 clean (was 35/35). Review independently
reproduced the RED-phase probe and additionally verified the
snapshot round-trip Observable is non-vacuous.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JPPXeKSUXUqcqvzNXY1rzJ
Rongsong Shen
2329dbf2a8
