release(v1.1.0): additive CPU-only generic numerical primitives

Adds 9 new top-level / sub-modules to the Rust API only (no Python
bindings yet), with at least one analytic unit test per module.

New Rust modules:
- optimal_control::matrix_riccati  (RK4 backward solver)
- timeseries_utils::nonsync_covariance  (Hayashi-Yoshida)
- timeseries_utils::wavelet  (Haar / Daubechies DWT and MODWT)
- risk_measures  (VaR, CVaR, projected sub-gradient CVaR minimisation)
- graph::laplacian + graph::spectral_clustering  (Jacobi + k-means++)
- topology  (Vietoris-Rips persistent homology, bottleneck distance)
- volterra  (Caputo Adams, Markovian lift, second-kind Volterra,
             Fourier inversion of characteristic functions)
- signatures  (truncated tensor signature, log-sig, random reservoir,
               Salvi-Cass-Lyons signature kernel, shuffle product)

All previously stable APIs untouched; abi3-py38 ABI preserved.
New module tests: 29/29 passing. Pre-existing 5 unrelated failures
unchanged.

docs/source/algorithms/wavelet.rst

@@ -0,0 +1,51 @@
+Discrete and Maximum-Overlap Wavelet Transforms
+================================================
+
+The module :code:`timeseries_utils::wavelet` provides Haar and Daubechies
+wavelet transforms with periodic boundary handling.
+
+Filter banks
+------------
+
+For an orthogonal scaling filter :math:`\{h_k\}_{k=0}^{L-1}` the quadrature
+mirror filter (QMF) is
+
+.. math::
+
+   g_k = (-1)^k\, h_{L - 1 - k},
+
+so that :math:`\sum_k h_k = \sqrt{2}` and :math:`\sum_k g_k = 0`.
+
+DWT (one level, periodic)
+-------------------------
+
+For an input vector :math:`x \in \mathbb{R}^N` with :math:`N` even,
+
+.. math::
+
+   a_n = \sum_{k=0}^{L-1} h_k\, x_{(2n + k)\bmod N},
+   \qquad
+   d_n = \sum_{k=0}^{L-1} g_k\, x_{(2n + k)\bmod N},
+   \qquad n = 0, \dots, N/2 - 1.
+
+Successive levels apply the same filter to the previous approximation
+:math:`a^{(j)}`.
+
+MODWT (Maximum Overlap)
+-----------------------
+
+The MODWT does not downsample: at level :math:`j`, the filter is dilated
+by inserting :math:`2^{j-1} - 1` zeros between successive taps and applied
+in a periodic convolution. The result is shift-invariant.
+
+API
+---
+
+.. code-block:: rust
+
+   pub enum WaveletFamily { Haar, Daubechies(u8) }
+   pub fn scaling_filter(family: WaveletFamily) -> Result<Vec<f64>>;
+   pub fn qmf(h: &[f64]) -> Vec<f64>;
+   pub fn dwt_step(x: &[f64], h: &[f64], g: &[f64]) -> (Vec<f64>, Vec<f64>);
+   pub fn dwt(x: &[f64], family: WaveletFamily, levels: usize) -> Result<Vec<Vec<f64>>>;
+   pub fn modwt_step(x: &[f64], h: &[f64], g: &[f64], level: usize) -> (Vec<f64>, Vec<f64>);