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/quadratic_impact_control.rst

@@ -41,6 +41,16 @@ $h'(t) = h(t)^2/γ - φ$ with $h(T) = A$.  When $γ = φ = A = 1$ the right-hand
    ax.set_title('Riccati fixed point  γ=φ=A=1')
    fig.tight_layout(); plt.show()
 
+
+
+
+
+.. AUTO-PLOT-BEGIN
+.. image:: ../_static/auto/algorithms__quadratic_impact_control/block_03_fig_01.png
+   :align: center
+   :width: 80%
+
+.. AUTO-PLOT-END
 .. image:: ../_static/v2/quadratic_impact_control/plot_01.png
    :align: center
    :width: 80%
@@ -60,6 +70,16 @@ Vary $A$, fix $γ = 1$, $φ = 0.25$, $T = 1$.
    ax.set_title('Riccati sensitivity to terminal weight')
    fig.tight_layout(); plt.show()
 
+
+
+
+
+.. AUTO-PLOT-BEGIN
+.. image:: ../_static/auto/algorithms__quadratic_impact_control/block_04_fig_01.png
+   :align: center
+   :width: 80%
+
+.. AUTO-PLOT-END
 .. image:: ../_static/v2/quadratic_impact_control/plot_02.png
    :align: center
    :width: 80%