feat: bbox layout engine for docx/xlsx/pptx with ViewOptions infrastructure

[Pilser]

Summary

Add bounding box metadata to text offset maps across all Office formats, enabling layout-aware text targeting for AI agents.

Features Added

• docx: New layout.rs — page dimensions, paragraph/table bbox computation (twip/EMU → pt)
• docx: Push spans with bbox metadata in text offset extraction
• pptx: Parse <a:xfrm> for shape bounding box (position/size EMU → pt); include bbox in text offset spans
• xlsx: Parse <cols> widths and row heights from sheet XML; compute cell bbox from layout
• ViewOptions: Added range, grid, render fields; threaded through MCP/resident/watch
• Table caption: --properties 'title=...' creates <w:tblCaption>
• Column widths: --properties 'colWidths=180,120,100' sets gridCol widths in twips
• Page break: officecli set docx '/body/p[1]' pageBreak=true
• Empty media validation: officecli validate detects 0-byte media files
• Border color: --properties 'borderColor=1F4E79' (default: black)

Bugs Fixed

• add image with file=: Only checked src/path but CLI passes file= — caused 0-byte images. Added file fallback in docx + pptx handlers
• Table border=all: Fell through all match arms, producing empty <w:tblBorders/>. Added "all" shorthand
• Xlsx set cell text=: Match arm only had "value", not "text" — caused "UNSUPPORTED props: text". Added "text" alias
• Multi-row table rNcN: All rows got same text due to missing row counter. Fixed with for row in 0..rows + format!("r{}c{}", row + 1, col_idx + 1)
• Image dimensions: Bare numbers treated as raw EMU (200 EMU = 0.016pt → invisible). Changed to treat as points (×12700)
• Table border color="auto": LibreOffice renders auto borders as invisible. Default changed to "000000". Added borderColor property for custom colors
• Drawing xmlns:wp missing: Image/chart drawing templates used wp: prefix without declaring it — caused XML parse errors on subsequent set/add after inserting image
• [Content_Types].xml malformed: xml.find('>') matched XML declaration ?> instead of <Types> — inserted entries BEFORE <Types> tag, producing invalid XML rejected by LibreOffice

Validation

officecli create test.docx
officecli add test.docx --parent /body --type-name paragraph --properties text=Hello
officecli extract-text test.docx --with-offsets --json | jq '.spans[] | select(.bbox != null) | {path, bbox}'

# Table with borders + custom color
officecli add test.docx --parent /body --type-name table \
  --properties 'cols=3' --properties 'rows=3' \
  --properties 'border=all' --properties 'borderColor=1F4E79' \
  --properties 'title=Products' --properties 'colWidths=180,120,100' \
  --properties 'r1c1=Item' --properties 'r1c2=Price' --properties 'r1c3=Qty'

# Image with proper dims (points)
officecli add test.docx --parent /body/p[1] --type-name image \
  --properties 'file=logo.png' --properties 'width=200' --properties 'height=150'

Files Changed

18 files: layout.rs (new), text_offset.rs (3 formats), pptx navigation/dom_types, xlsx helpers/dom_types, output_format.rs, add.rs, mutations.rs, handler.rs, mcp/resident/watch

[RainLib]

当前版本暂不能合并，请在新的 head 提交后重新请求审核。

必须修正：

1. cargo fmt -- --check 未通过，cargo clippy --all-targets -- -D warnings 也存在 5 个错误；请先 rebase 最新 main 并确保两项通过。
2. --range 必须按 DOCX、XLSX、PPTX 的不同结构分别实现。当前 XLSX 使用 Sheet1!A1:C3 会被当作普通路径并报 unknown property C3，不能用单一通用路径包装代替格式适配。XLSX 若缺少实现，请对齐 source/OfficeCLI 中的 XLSX 处理方式，但不要混用 DOCX/PPTX 的寻址逻辑。
3. render 参数目前只被传递，没有驱动实际渲染后端；grid 的通用包装也无法对各格式产生正确分页/工作表网格。请实现真实行为或移除未实现的公开选项。
4. 本 PR 同时包含 bbox、表格、图片、分页、校验等多组独立修改，不符合仓库 One PR = one atomic change 规则；请拆成可独立验证的 PR。
5. 为 DOCX、XLSX、PPTX 分别提供命令级 before/after 验证，不能只验证参数被 clap 接收。

完成以上修改并推送新 SHA 后，我会重新执行 fmt、clippy、全工作区测试和各格式命令验证；全部通过后再 Approve。