Replay: deterministic record & playback (#4)

Add deterministic record/playback for a run.

Recording captures `(seed, config hash, ordered tick-tagged commands)` and re-simulates on playback — no state snapshots. `DotaFactory.exe --replay <file>` re-plays a recorded run view-only with manual speed/pause.

Reviewed-on: #4
Co-authored-by: Malte Langkabel <malte.langkabel@gmail.com>
Co-committed-by: Malte Langkabel <malte.langkabel@gmail.com>

src/lib/sim/CommandSerializer.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <memory>
+#include <string>
+
+struct Command;
+
+// Serializes a command to a single-line, space-delimited token sequence for the
+// replay file (see docs/replay_design.md "File format: line-oriented ...").
+// Config ids (building types, recipes, items, modules) are whitespace-free
+// identifiers, so space delimiting is unambiguous; variable-length parts are
+// length-prefixed so the matching parser (added in Phase 3) is unambiguous.
+//
+// Reset is a file boundary (it rolls the replay file), not a stream entry, so it
+// is never serialized here.
+std::string serializeCommand(const Command& command);
+
+// Inverse of serializeCommand: parses the command token sequence (the part of a
+// replay line after the leading tick) back into a Command. Returns nullptr if the
+// tokens are malformed or reference an unknown building type.
+std::shared_ptr<Command> parseCommand(const std::string& tokens);