Merge PR 1 (codecs, now on current main) into PR 3

Brings split/tiff-extra-samples-codecs at e6fca054, which merged main
1695f323. Conflicts:
- crates/io/src/lib.rs: main moved PSD import into import_psd(); it now
  passes PsdImportOptions::default().
- PsdExportOptions (psd_export.rs, tiff_layers.rs): main's new
  read_linked_files next to this branch's photoshop_spot_polarity.
- docs: main's newer status lines and rows, with this branch's TIFF
  statements re-applied (dated 2026-10-23). docs/scorecard.md is main's
  and is regenerated after PR 2 is merged too.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

book/src/formats/pcraft.md

@@ -8,8 +8,11 @@ tiles/<blake3>.zst
 blobs/<blake3>.zst
 thumb.png
 composite/preview.png
+save.lock
 ```
 
+`save.lock` exists only in directory bundles: a save holds an OS file lock on it while it writes objects, publishes the manifest and removes unreferenced objects, so concurrent saves of one bundle take turns. It is empty, and readers ignore it.
+
 The manifest is versioned and describes the document tree. Tiles and blobs are content-addressed. Loaders verify ZIP entry bounds and CRCs; document content also uses stored hashes to detect mismatched or corrupted tile/blob content. Unsupported newer format versions fail explicitly.
 
 ## Implemented load limits

book/src/formats/raster-formats.md

@@ -19,6 +19,7 @@ Every route that writes a document to a flat format (Save As, the CLI, MCP `doc_
 - Formats without transparency (JPEG, Radiance HDR) get the image composited over white, as Export As and Quick Export do; in CMYK, white is no ink.
 - Formats that can't embed an ICC profile (GIF, BMP, TGA, QOI, ICO, Netpbm/PFM) get RGB documents in another profile (linear light, Display P3, …) converted to sRGB through the colour engine (perceptual intent), since an untagged file is read as sRGB. OpenEXR and Radiance HDR get linear sRGB instead (linear gray for a grayscale OpenEXR), which is how they are tagged when opened.
 - TGA, as Photoshop's Targa: an RGB Targa is 24 or 32 bits per pixel. Save As and Save a Copy ask (Targa Options, starting at 32 with an alpha channel, else 24); Export As has a Resolution choice (Auto, 24 or 32 bits/pixel); scripts pass `tgaBits` (`--tga-bits` on the CLI). At 32 bits the document's alpha channel is the file's alpha when it has exactly one (spot channels don't count; with several, none is used), and the colours are written exactly, never premultiplied or cleared where the alpha is 0, so a game texture's mask and its colours both survive. Without a usable alpha channel the layers' transparency is the alpha (opaque without any). 24 bits write no alpha, compositing transparency over white. Without a choice: 32 with an alpha channel or transparency, else 24. A 32-bit Targa opens as an opaque Background with its alpha as "Alpha 1", so it round-trips. Grayscale Targas are 8-bit.
+- JPEG, as Photoshop's JPEG Options: File › Save, Save As and Save a Copy ask for the Quality on Photoshop's 0–12 scale (with its Low, Medium, High and Maximum presets) and a Format Option: Baseline ("Standard"), Baseline Optimized (Huffman tables fitted to the image) or Progressive. The quality starts at the opened JPEG's own quality, else at the Export preference's JPEG quality; left there, an opened JPEG is written at exactly its own quality. Scripts pass `"quality": 0..12` and `"jpegFormat": "baseline" | "optimized" | "progressive"` (on the CLI, `--quality` on the encoder's 1–100 scale and `--jpeg-format`) and aren't asked; recorded actions replay the answer. The scale maps onto the encoder's 1–100 as `round(q / 12 × 99 + 1)`. RGB JPEGs are written 4:2:0, where Baseline Optimized keeps the standard tables for now (Gray and CMYK, written 4:4:4, get fitted ones). Matte, the progressive scan count (Scans 3–5) and the file-size preview aren't offered.
 - DDS, for game and 3D textures: Save As and Save a Copy ask (DDS Options) for the compression (None, uncompressed and lossless; BC1/DXT1, whose alpha is on or off; BC2/DXT3; BC3/DXT5) and whether to generate mipmaps (the full chain down to 1×1, each level a box filter of the one above). Scripts pass `ddsCompression` (`none`, `bc1`, `bc2`, `bc3`) and `ddsMipmaps` (`--dds-compression`, `--dds-mipmaps` on the CLI). Opening one reads its top mip level.
 
 Flat TIFF and JPEG exports of composited CMYK documents convert the RGB composite back through