docs(v2.0.0-alpha.3): inline plot injection across the entire doc tree

Add scripts/inject_doc_plots.py that scans every .md and .rst page under
docs/source/, executes each Python code-block in an isolated namespace
with a non-interactive matplotlib backend, captures every figure
produced, and inserts an inline image directive immediately after the
code-block.  Markers AUTO-PLOT-BEGIN/END make the injection idempotent
on re-runs.  Blocks that fail to execute or produce no figure are left
untouched.

Add a transparent __getattr__ fallback in python/optimizr/__init__.py
that forwards any unresolved top-level attribute to the compiled _core
extension.  This lets all v1.x and v2.0 doc samples that use
'from optimizr import X' (estimate_ou_params_py, linear_bsde_constant_coeffs,
mmd_gaussian, ...) execute as written.

Augment the OU Parameter Estimation example
(docs/source/algorithms/optimal_control.md) with a two-panel
visualization (simulated path plus empirical/theoretical autocorrelation).

Net effect: 14 doc pages now display matplotlib plots inline directly
under the code that produced them -- including the OU page, point
processes, Grid Search, HMM, MCMC, plus the 8 v2.0 RST pages.

docs/source/algorithms/mckean_vlasov.rst

@@ -41,6 +41,16 @@ Interacting-particle Euler scheme for $dX_t = θ(\bar X_t - X_t) dt + σ dW_t$ (
    ax.set_title('Mean-reverting McKean–Vlasov — 200 particles')
    fig.tight_layout(); plt.show()
 
+
+
+
+
+.. AUTO-PLOT-BEGIN
+.. image:: ../_static/auto/algorithms__mckean_vlasov/block_03_fig_01.png
+   :align: center
+   :width: 80%
+
+.. AUTO-PLOT-END
 .. image:: ../_static/v2/mckean_vlasov/plot_01.png
    :align: center
    :width: 80%
@@ -54,6 +64,16 @@ Interacting-particle Euler scheme for $dX_t = θ(\bar X_t - X_t) dt + σ dW_t$ (
    ax.set_title('Marginal density at t = 0 and t = T')
    fig.tight_layout(); plt.show()
 
+
+
+
+
+.. AUTO-PLOT-BEGIN
+.. image:: ../_static/auto/algorithms__mckean_vlasov/block_04_fig_01.png
+   :align: center
+   :width: 80%
+
+.. AUTO-PLOT-END
 .. image:: ../_static/v2/mckean_vlasov/plot_02.png
    :align: center
    :width: 80%