feat(xrd): add XRD import and processing

[Limdongcheng]

Summary

• Import Rigaku powder XRD data from .rasx, FI-layout .raw, and recognized RAS_RAW profile text while preserving acquisition metadata.
• Route shared .raw paths by file signature so Waters directories and unsupported RAW files are not misclassified.
• Integrate XRD state, field capabilities, project persistence, CLI/automation inspection, processed-data export, and default XRD plotting through the existing crate boundaries.
• Add SNIP background subtraction, Savitzky-Golay smoothing, maximum/area normalization, undo/reset, and parameter validation.
• Make shared task cards draggable and align vertical resize handles with the visible bottom-right corner.
• Document XRD import and processing in English and Simplified Chinese.
• Defer peak detection, peak tables, reference-card search, and phase matching to follow-up work.
• No vendor sample files or third-party reference-card data are included; validation used local user-owned files outside the repository.

Validation

• cargo pr-check
• npm run build in docs/ (71 pages)
• Focused XRD I/O, processing, project round-trip, RAW discovery, and task-card interaction/layout tests
• Opened and processed a real 8,701-point Rigaku FI RAW pattern in the macOS development app
• Visually verified XRD task-card movement and resize-handle placement
• git diff --check

UI display logic

• New or changed actions go through the command catalog (CommandId + describe) and are searchable in command palette. XRD controls are panel-local; the existing Processing action remains cataloged.
• Hiding is only used at the group level; no transient hide behavior was added.
• No layout changes occur in background jobs or on completion, and panels do not auto-close.
• The XRD Processing task opens from an explicit user action and immediately exposes its processing controls.
• User-facing documentation is updated in matching English and Simplified Chinese pages.