Add atst examples in ASE interfaces examples

[QuantumMisaka]

Reminder

• I have read AGENTS.md and docs/developers_guide/agent_governance.md.
• I have linked an issue or explained why this PR does not need one.
• I have added adequate unit tests and/or case tests, or explained why not.
• I have listed the exact verification commands run and their results.
• I have described user-visible behavior changes, including INPUT parameter changes.
• I have explained core-module impact for ESolver, HSolver, ElecState, Hamilt, Operator, Psi, or other source/ changes.
• No governance exception is requested.

Linked Issue

No linked issue. This PR only adds optional ATST-Tools workflow examples and a short README entry under the ASE interface examples.

Unit Tests and/or Case Tests for my changes

• git diff --check -- interfaces/ASE_interface/README.md interfaces/ASE_interface/examples/atst_tools: passed.
• Conflict-marker scan over interfaces/ASE_interface/README.md interfaces/ASE_interface/examples/atst_tools: passed.
• conda run -n atst-dev atst config validate ... --print-normalized for all added YAML configs: passed.
• conda run -n atst-dev atst run --dry-run ... for all added workflow configs: passed.
• conda run -n atst-dev atst abacus prepare ... and atst abacus collect ... for the helper workflow: passed.
• No upstream ABACUS case test is added because ATST-Tools remains an optional external workflow layer and no ABACUS core behavior is changed.

Exact Verification Performed

• Commands run:
  • git diff --check -- interfaces/ASE_interface/README.md interfaces/ASE_interface/examples/atst_tools
  • conflict-marker scan over interfaces/ASE_interface/README.md interfaces/ASE_interface/examples/atst_tools
  • generated inputs with each added make_inputs.py
  • conda run -n atst-dev atst config validate <config> --print-normalized for relax_si, neb_si, sella_h2, ccqn_h2, both md_si configs, and abacus_helper
  • conda run -n atst-dev atst run --dry-run <config> for relax_si, neb_si, sella_h2, ccqn_h2, and both md_si configs
  • conda run -n atst-dev atst abacus prepare config.yaml --structure inputs/init.extxyz --output-dir prepared_abacus --force
  • conda run -n atst-dev atst abacus collect prepared_abacus --output abacus_results.json
• Result summary: all listed checks completed successfully in the installed atst-tools environment.
• Checks not run, with reason: full ABACUS numerical runs were not launched in CI because these examples are optional external workflow examples and require a configured ABACUS runtime environment.

What's changed?

• Adds optional ATST-Tools examples for relax, NEB, Sella, CCQN, MD, and ABACUS input preparation under interfaces/ASE_interface/examples/atst_tools/.
• Documents ATST-Tools as an optional workflow layer on top of abacuslite.
• Does not add ATST-Tools as an abacuslite dependency and does not change ABACUS runtime behavior.

Governance Checklist

• Global dependencies: no GlobalV, GlobalC, or PARAM code references are added.
• Default parameters: no existing interface default arguments are changed.
• Headers: no header dependencies are changed.
• Line endings: changed text files use LF.
• Build linkage: no new ABACUS source files are added, so no CMakeLists.txt update is needed.
• Documentation: the ASE interface README and the new example README document the optional workflow usage.
• CodeRabbit: automatic review can be requested by maintainers if needed.

INPUT Parameter Changes

• Parameters added/removed/changed: none.
• docs/parameters.yaml updated: not applicable.
• docs/advanced/input_files/input-main.md updated: not applicable.
• No INPUT documentation update is required because this PR only adds optional example YAML files for ATST-Tools and does not change ABACUS INPUT semantics.

Core Module Impact

• Affected core modules: none.
• Risk summary: examples and documentation only; no source/ files are changed.
• Compatibility or performance impact: none expected for ABACUS core modules.

Governance Exception

• Rule: none.
• Reason: no exception is requested.
• Scope: not applicable.
• User or maintenance risk: not applicable.
• Why the normal rule cannot be followed now: not applicable.
• Follow-up cleanup plan: not applicable.
• Requested approver: not applicable.