Finish viewer and calculation workflows

[newtontech]

Summary

• ship the production 3Dmol viewer editing surface with constraints, undo/redo, supercells, trajectories, export, and bounded source writeback
• wire the viewer through the compute worker, structure cache, and incremental parser; keep full editing through 10,000 atoms and use deterministic read-only LOD above that threshold
• connect calculator, Jobs, analyzer, result, cancellation, restart, trajectory, and export paths to real handlers
• vendor required visualization runtime assets, verify them in the packaged VSIX, and add desktop/narrow source and packaged visual smoke coverage
• incorporate the completed issue Harden the newtontech.openqc 0.0.1 release and dependency pipeline #236 release pipeline through d14151c so package identity and release gates stay consistent
• synchronize README, CHANGELOG, and agent memory with the shipped behavior

Tests

• make format
• make lint (passes with one existing non-error curly warning in src/agent/OpenQCToolRegistry.ts)
• make typecheck
• make test (95 suites, 1712 passed, 2 skipped; 91.26% statements)
• make check (including production audit: 0 vulnerabilities)
• Python bridge unittest discovery (27 passed)
• VSIX package + verification (596 files, 2.92 MiB)
• release checksum and CycloneDX SBOM generation
• source desktop/narrow visual smoke
• packaged VSIX desktop/narrow visual smoke

Local validation ran on the available Node 26 runtime because the installed Node 22 binary was killed by the host before startup; CI and release workflows enforce Node 22.

Fixes #238