Merge PR #565: Files: save and open outlines as RTF

Conflicts:
crates/engine/src/cmd/file.rs: export spec keeps main's transparentBackground and adds rtf; probe_clips (main) and outline_text (PR) both kept
docs/file-format-parity.md: PR's outline row (RTF now read) with main's .md wording, main's PNG row

docs/file-format-parity.md

@@ -25,7 +25,7 @@ PowerPoint opens and saves; Viewer = opens only).
 | `.thmx` Office theme | Viewer | theme only (Design › Browse for Themes…) | no | Browse for Themes takes a `.thmx`'s colours, fonts and effects; a `.pptx` or `.potx` brings its slide master and layouts as well, and slides move to the matching layouts (#807). A `.thmx`'s own master and layouts aren't read yet | `crates/pptx/src/lib.rs` (`import_theme_tests`), `crates/engine/src/cmd/design.rs` (`browse_theme_tests`) |
 | `.deckcraft` native (zip + JSON) | n/a | yes (also `.slidecraft`) | yes | Lossless for the DeckCraft model, forward compatible | `crates/format` tests |
 | PDF | export | no | yes | Slides, notes pages, handouts (1–9); real-text layer with embedded subsets, links, bookmarks. Slide artwork is a raster image at print resolution, not vector | `crates/pdf` tests |
-| Outline `.rtf` / `.txt` | export (RTF), import (outline) | `.txt` outline; `.md` as Markdown (headings are slides, list items bullets) (`slide.fromOutline`) | `.txt` outline | No RTF | engine tests |
+| Outline `.rtf` / `.txt` | export (RTF), import (outline) | `.txt` and `.rtf` outline; `.md` as Markdown (headings are slides, list items bullets) (open, drop, `slide.fromOutline`) | `.txt` and `.rtf` outline | — | format + engine tests |
 | PNG / JPEG slide images | export | n/a | yes (`file.export`, `deckcraft-cli render`) | Matches the editor's renderer. PNG `pHYs` and JPEG JFIF density are `scale` × 72 dpi (default scale 2 is 144 dpi), so Preview shows the slide's real size. PNG can leave the slide background out (`transparentBackground`, Export… “Transparent background”, `deckcraft-cli render --transparent`), so only the slide's content is opaque (#784) | render, engine, UI and CLI tests |
 | TIFF / BMP / GIF slide images | export | n/a | no | Easy (the `image` crate writes them) | none |
 | Animated GIF of the deck | export | n/a | yes (`file.export` format `gif`, Export…, `deckcraft-cli`, MCP `export`) | One frame per slide from the slide renderer; size small/medium/large/extra large or 16–3840 px wide, 0.1–600 s per slide, loop forever or play once, slide range, hidden slides skipped; a 256-colour palette per frame (exact, or NeuQuant above 256 colours). Transitions and build animations are not animated | `crates/engine/src/gif_export.rs` tests (decoded frames, size, delay, loop, hidden slides, hostile params), MCP, CLI and export dialog tests |

docs/parity-checklist.md

@@ -9,12 +9,12 @@ The summary between `<!-- SUMMARY -->
 |---|---|---|---|---|---|
 | P0 | 72 | 61 | 11 | 0 | 92% |
 | P1 | 65 | 45 | 16 | 4 | 82% |
-| P2 | 54 | 17 | 25 | 12 | 55% |
+| P2 | 54 | 18 | 24 | 12 | 56% |
 
 | Area | Parity |
 |---|---|
 | Application shell | 81% |
-| Files | 75% |
+| Files | 76% |
 | Slides | 92% |
 | Views | 98% |
 | Masters & themes | 92% |
@@ -64,7 +64,7 @@ Open P0 items: Contextual tabs (Shape Format, Picture Format, Table Design/Layou
 | Files | Document properties | P2 | D |
 | Files | Export to PDF (slides, notes pages, handouts; text layer, links, bookmarks; vector artwork pending) | P0 | P |
 | Files | Export slides as PNG/JPEG | P0 | D |
-| Files | Export outline / RTF | P2 | P |
+| Files | Export outline / RTF | P2 | D |
 | Files | Export video (MP4) / animated GIF (GIF: one frame per slide, no transitions; no video) | P2 | P |
 | Files | Print (slides, handouts, notes, outline) | P1 | M |
 | Files | Password protection | P2 | M |