README: refresh package layout (gate->gates, add ft_solver/sampler/optimizers/examples)

Author: rezah

README.md

@@ -11,8 +11,15 @@ Current package version: `0.1.1` (from `pyproject.toml` / `pepsy.__version__`).
   - `boundary_states.py`: boundary state initialization (`BdyMPS`)
   - `boundary_sweeps.py`: sweep/contraction runner (`CompBdy`)
   - `boundary_metrics.py`: input preparation + contraction (`build_bra_ket`, `contract_boundary`, `BoundaryContractResult`)
-  - `optimize_sweep.py`, `optimize_global.py`, `optimize_energy.py`, `gate.py`, `gradient_solver.py`
-  - `fit.py`, `core.py`, `_backend_utils.py`, `_backend_linalg.py`
+  - `gates.py`: gate application (`gate`, `gate_simple`, `renorm_gauge`) with long-range SWAP routing
+  - `core.py`: lattice maps (`OneDMap`), state/MPO/PEPO builders, backend defaults
+  - `ham.py`: Hamiltonian helpers
+  - `optimize_sweep.py`, `optimize_global.py`, `optimize_energy.py`: optimizers
+  - `optimize_mps.py`, `optimize_mpo.py`: `MpsOptimizer`, `MpoOptimizer`
+  - `gradient_solver.py`, `ft_solver.py`: gradient-based and FT/FD solvers
+  - `sampler.py`: `MpsSampler` and related sampling utilities
+  - `fit.py`, `_backend_utils.py`, `_backend_linalg.py`, `_backend_linalg_torch.py`, `_backend_linalg_jax.py`
+- `examples/`: runnable examples (e.g. `MpsMagnetization/` 2D ITF Trotter MPS evolution)
 - `docs/`: Sphinx documentation source
 - `tests/`: package tests