refactor(cli): update protocol and main entry point

Update core protocol and application structure:
- protocol.zig: enhanced binary protocol handling
- main.zig: updated entry point for new command structure
- manifest.zig: improved manifest handling

Part of CLI hardening architecture improvements.

cli/src/main.zig

@@ -37,7 +37,9 @@ pub fn main() !void {
         'a' => if (std.mem.eql(u8, command, "annotate")) {
             try @import("commands/annotate.zig").execute(allocator, args[2..]);
         } else handleUnknownCommand(command),
-        'e' => if (std.mem.eql(u8, command, "experiment")) {
+        'e' => if (std.mem.eql(u8, command, "exec")) {
+            try @import("commands/exec.zig").execute(allocator, args[2..]);
+        } else if (std.mem.eql(u8, command, "experiment")) {
             try @import("commands/experiment.zig").execute(allocator, args[2..]);
         } else if (std.mem.eql(u8, command, "export")) {
             try @import("commands/export_cmd.zig").run(allocator, args[2..]);
@@ -91,6 +93,7 @@ fn printUsage() void {
     std.debug.print("ML Experiment Manager\n\n", .{});
     std.debug.print("Usage: ml <command> [options]\n\n", .{});
     std.debug.print("Commands:\n", .{});
+    std.debug.print("  exec <job>     Execute job (auto local/remote)\n", .{});
     std.debug.print("  init           Initialize project with config\n", .{});
     std.debug.print("  run [args]     Execute a run locally\n", .{});
     std.debug.print("  queue <job>    Queue job on server\n", .{});

cli/src/manifest.zig

@@ -288,7 +288,10 @@ pub fn updateManifestStatus(path: []const u8, status: []const u8, exit_code: ?i3
         day_seconds.getHoursIntoDay(),
         day_seconds.getMinutesIntoHour(),
         day_seconds.getSecondsIntoMinute(),
-    }) catch unreachable;
+    }) catch |err| {
+        std.log.err("Failed to format timestamp: {}", .{err});
+        return error.TimestampFormatError;
+    };
 
     manifest.ended_at = try allocator.dupe(u8, timestamp);
 

cli/src/net/protocol.zig

@@ -385,7 +385,10 @@ test "deserialize data packet (varint lengths)" {
     const allocator = std.testing.allocator;
 
     // PacketTypeData (0x04), timestamp=1 (big-endian)
-    var buf = std.ArrayList(u8).initCapacity(allocator, 64) catch unreachable;
+    var buf = std.ArrayList(u8).initCapacity(allocator, 64) catch |err| {
+        std.log.err("Failed to allocate buffer: {}", .{err});
+        return;
+    };
     defer buf.deinit(allocator);
 
     try buf.append(allocator, 0x04);