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/agent_based.rst

@@ -40,6 +40,16 @@ Generic interacting-agent simulator (`consensus_dynamics`) — linear bounded-co
    ax.set_title('Bounded-confidence consensus, α = 0.3')
    fig.tight_layout(); plt.show()
 
+
+
+
+
+.. AUTO-PLOT-BEGIN
+.. image:: ../_static/auto/algorithms__agent_based/block_03_fig_01.png
+   :align: center
+   :width: 80%
+
+.. AUTO-PLOT-END
 .. image:: ../_static/v2/agent_based/plot_01.png
    :align: center
    :width: 80%
@@ -56,6 +66,16 @@ Generic interacting-agent simulator (`consensus_dynamics`) — linear bounded-co
    ax.set_title('Convergence rate vs averaging weight α'); ax.legend(); ax.grid(alpha=0.3)
    fig.tight_layout(); plt.show()
 
+
+
+
+
+.. AUTO-PLOT-BEGIN
+.. image:: ../_static/auto/algorithms__agent_based/block_04_fig_01.png
+   :align: center
+   :width: 80%
+
+.. AUTO-PLOT-END
 .. image:: ../_static/v2/agent_based/plot_02.png
    :align: center
    :width: 80%