docs(skills): add dpdata minimizer skill

skills/dpdata-minimizer/SKILL.md

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+---
+name: dpdata-minimizer
+description: Minimize geometries with dpdata minimizer plugins via System.minimize(), including how minimizers relate to drivers (ASEMinimizer needs a dpdata Driver) and how to list supported minimizers (ase/sqm). Use when doing geometry optimization/minimization through dpdata Python API.
+---
+
+# dpdata-minimizer
+
+Use dpdata “minimizer plugins” to **optimize/minimize geometry** and return a `dpdata.LabeledSystem`.
+
+## Key idea
+
+- A **Minimizer** performs geometry optimization (updates coordinates) and returns labeled results.
+- dpdata exposes this as:
+
+```python
+System.minimize(*args, minimizer: str|Minimizer, **kwargs) -> LabeledSystem
+```
+
+## List supported minimizer keys (runtime)
+
+```python
+from dpdata.driver import Minimizer
+
+print(sorted(Minimizer.get_minimizers().keys()))
+```
+
+In the current dpdata repo, minimizer keys include:
+
+- `ase`
+- `sqm`
+
+## Relationship to drivers (important)
+
+Some minimizers require a **dpdata Driver object**.
+
+Example: `ASEMinimizer` takes a dpdata `Driver` in its constructor:
+
+- `minimizer="ase"` requires `driver=<dpdata Driver>` (e.g. the ASE driver wrapping an ASE calculator).
+
+So you generally do:
+
+1. Construct a driver
+1. Construct a minimizer (or let dpdata do it by passing the right kwargs)
+1. Call `System.minimize(...)`
+
+## Runnable example: ASE minimizer with an ASE calculator
+
+Use uv inline script metadata so the example runs reproducibly with `uv run`.
+
+```python
+# /// script
+# requires-python = ">=3.12"
+# dependencies = [
+#   "dpdata",
+#   "numpy",
+#   "ase",
+# ]
+# ///
+
+import numpy as np
+from ase.calculators.emt import EMT
+
+from dpdata.driver import Driver
+from dpdata.system import System
+
+open("tmp.xyz", "w").write("""2\n\nH 0 0 0\nH 0 0 0.74\n""")
+
+sys = System("tmp.xyz", fmt="xyz")
+
+# Build a dpdata driver that can provide energies/forces to ASE optimizers.
+ase_driver = Driver.get_driver("ase")(calculator=EMT())
+
+# Minimize using the ASE minimizer plugin.
+# NOTE: ASEMinimizer expects `driver` (not `calculator`) as input.
+ls = sys.minimize(minimizer="ase", driver=ase_driver, fmax=0.05, max_steps=5)
+
+print("coords", np.array(ls.data["coords"]).shape)
+print("energies", np.array(ls.data["energies"]))
+print("forces", np.array(ls.data["forces"]).shape)
+```
+
+## Notes / gotchas
+
+- `System.minimize(...)` accepts either a minimizer key string or a Minimizer object.
+- If you previously used `System.predict(driver="ase", calculator=...)`, be aware that minimization is different: you need to pass a **driver** into the minimizer (ASEMinimizer does not accept `calculator=`).
+- `sqm` minimizer requires AmberTools `sqm` executable and typically won’t be runnable in CI.