Add graphical single-entry molecular workbench

[PerinMu]

Summary

• add an optional bilingual Streamlit workbench for entering molecules and sequences one record at a time
• provide a visual peptide editor for residue-position PTMs, N/C termini, backbone N-methylation, D residues, and editable generated notation
• expose representation conversion, Morgan/RDKit/MACCS/Atom Pair/Torsion/k-mer fingerprints, and molecular descriptors
• show result cards with formula, exact mass, charge, heavy atoms, canonical SMILES, 2D structure, and per-result downloads
• retain successful entries in session history with individual removal and complete JSON/CSV export
• add a custom side-chain/N-terminal/C-terminal modification library with shared runtime validation and registry import/export
• expose both moltranscode gui and moltranscode-gui while keeping Streamlit optional
• document installation, the manual workflow, local-only processing, and network-binding precautions

Validation

• ruff check .
• pytest: 64 passed
• Streamlit AppTest: bilingual UI, visual multi-PTM peptide editing, terminal groups, InChIKey conversion, result metrics, 2D drawing, history, and downloads
• Streamlit AppTest: custom AzidoLys registration immediately available in the peptide editor
• Streamlit AppTest: single SMILES to MACCS fingerprint workflow
• live local server health check on 127.0.0.1:8501
• built moltranscode-0.2.0-py3-none-any.whl and verified GUI modules plus entry points are packaged

Notes

The GUI processes one record at a time and retains history only for the active session. Batch workflows remain in the CLI. It exports existing schema_version 1 registry JSON and does not upload structures to a hosted service.