Desktop workbench overhaul: toolbar options, input/constants/result redesign, design-token pass

[yilibinbin]

Summary

Desktop GUI overhaul for DataLab's workbench: toolbar-driven options, a redesigned
input/constants/result layout, on-demand LaTeX, a full design-review token pass, plus a
batch of UX polish and bug fixes accumulated on this branch. One Python core, two frontends
— desktop changes only; the web app and compute layers are untouched.

Highlights

Layout / workbench

• Two-pane workbench (config+data | result) with a result-heavy ~1:3 default ratio.
• Input data + constants merged into 输入数据 / 常数 sheet tabs; each tab self-contained.
• Input-area expand/collapse toggle with a smooth 220ms splitter animation.
• Left column unified into [输入数据] + [one config card] per mode; mode selector on the toolbar.
• Result overview → compact clickable toolbar status chip; history moved to a toolbar popup.

Input / constants UX

• Removed the 使用数据文件 checkbox — a non-empty file path now takes precedence over the
  manual editor (which greys/hides live when a path is entered). Same for constants.
• Constants card gained a 输入常数 title, an N 行 row-count, and a ? help button (matching the
  data card); both input cards now carry a consistent border + padding.
• Excel-like block copy (Ctrl/Cmd+C → TSV) in the data/constants tables.

LaTeX / result

• On-demand 生成 TeX / 预览 PDF (no generate-checkbox); tex-rebuild inputs persist in the
  workspace so it works after reopen without recomputing.
• 不确定度位数 moved to the result panel with live re-render.
• Fitting model line honours the digit / scientific toggles; long compile-error dialogs no longer
  push OK off-screen; result font-size control live-updates.

Feature removal

• Removed the 单位标注 (units) feature end-to-end on the UI side (not general enough); the
  display-only backend is left as harmless dead code and old workspaces still open.

Design-review token pass (theme.py)

• Converged 3–4 near-duplicate hexes per role into semantic tokens
  (text_primary/text_muted/border/card_bg/region_bg/surface_raised/surface_hover).
• Radius collapsed to a 2-tier scale (RADIUS_CARD=8 / RADIUS_CONTROL=6); one canonical
  CARD_PADDING; formula-preview border fixed; fixed-white tutorial card text pinned dark.

Precision / workspace correctness

• Lossless mpf workspace serialization (was two-sided precision loss on reopen).
• Guarded workspace capture against missing data/constants files.

Review gates already passed on this branch

• Three-model serial adversarial review (Claude → Codex → Gemini) across multiple rounds;
  all confirmed findings fixed (mpf precision, theme-toggle stale styles, animation-fight,
  tutorial contrast, file-precedence live feedback, …). Gemini's agy channel timed out on the
  last two rounds — its lens was covered by direct code inspection and noted as such.
• /simplify 4-agent cleanup pass (reuse / simplification / efficiency / altitude): radius
  convergence finished, per-keystroke constants refresh gated, dead widget removed.
• Iterative user acceptance on the live GUI throughout.

Test plan

• QT_QPA_PLATFORM=offscreen pytest -q — full suite green (a couple of files run separately due
  to an offscreen Qt-teardown hang unrelated to these changes).
• Per-round targeted suites (theme tokens/spacing, two-pane layout, input/constants tabs,
  constants editor, formula preview, workspace controller, option reachability) all pass.
• Regression tests added for: file-precedence dimming, expand/collapse restore, formula-preview
  pixmap inset, constants row-count + control-row placement, theme-toggle restyle, mpf round-trip.

Requesting

CodeRabbit review before merge to main.

Summary by CodeRabbit

• New Features
  • On-demand LaTeX generation with a non-modal preview dialog (TeX source + compiled PDF).
  • History panel now collapses by default, with a toolbar popup; added a compact result overview popover and an always-visible result status strip.
  • Desktop toolbar option controls now open real non-modal dialogs.
• Bug Fixes
  • Excel-like block copy (Ctrl/Cmd+C → TSV) for table selections; improved formula preview border visibility and refreshed embedded constants/editor styling.
  • Web: fixed docs TOC heading anchors; added rate-limiting for heavy compute POST requests.
• Refactor
  • Merged two-pane workbench layout with improved resize/height behavior.
  • LaTeX numeric digit grouping supports native vs app-side grouping (engine-adaptive where available); removed TeX/PDF result tabs.