subplot_titles Ordering Inconsistent with Documentation

The subplot_titles argument in make_subplots appears to assign titles in column-major order (down columns) rather than the documented row-major ("reading") order.

Here is a Minimal Reproducible Example.

```Julia
using PlotlyJS

# Create a 2x2 subplot with numbered titles
p = make_subplots(
rows=2,
cols=2,
subplot_titles=["1" "2"
"3" "4"]
)

# Add traces to visualize the order
for i in 1:2, j in 1:2
add_trace!(p, PlotlyJS.scatter(x=[1], y=[1]), row=i, col=j)
end

display(p)
```
**Current Behavior:**
The titles are assigned in this order:
1 3
2 4

**Expected Behavior:**
According to the documentation, the titles should be assigned in reading order (left-to-right, then top-to-bottom):
1 2
3 4

**Version info**
`Julia Version 1.10.0
Commit 3120989f39b (2023-12-25 18:01 UTC)
Build Info:
Official https://julialang.org/ release
Platform Info:
OS: macOS (arm64-apple-darwin22.4.0)
CPU: 10 × Apple M1 Pro
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-15.0.7 (ORCJIT, apple-m1)
Threads: 1 on 8 virtual cores`
Please provide the following:

**Output of pkg"status"**
`Status `~/.julia/environments/v1.10/Project.toml`
⌃ [ad839575] Blink v0.12.5
⌃ [336ed68f] CSV v0.10.14
⌃ [a6e380b2] ControlSystems v1.10.0
[717857b8] DSP v0.7.10
[a93c6f00] DataFrames v1.7.0
[7a1cc6ca] FFTW v1.8.0
⌃ [5789e2e9] FileIO v1.16.3
⌅ [cd3eb016] HTTP v0.9.17
[caafb194] Kaleido v0.2.7
⌃ [b964fa9f] LaTeXStrings v1.3.1
[58dd65bb] Plotly v0.4.1
[a03496cd] PlotlyBase v0.8.19
⌃ [f0f68f2c] PlotlyJS v0.18.14
[f2990250] PlotlyKaleido v2.2.5
⌃ [91a5bcdd] Plots v1.40.8
⌃ [c3e4b0f8] Pluto v0.17.7
[80ea8bcb] PortAudio v1.3.0
⌃ [df1fea92] SignalAnalysis v0.9.0
⌃ [90137ffa] StaticArrays v1.9.7
[40c74d1a] TableView v0.8.0
[8149f6b0] WAV v1.2.0
[f7e6163d] Kaleido_jll v0.2.1+0
`