release notes: the 1.3.0 entries the merged PRs did not leave behind

[Jing-yilin]

What this changes

## Unreleased had only the placeholder. A release cut from it would have published generated commit subjects, while 1.2.0..main is 84 commits including a new skill and several canvas features.

Reconstructed from the log and grouped the way the released sections are (same job as #71):

• The canvas — inspect the board on the canvas (not a copy in the panel), fold and hide layers, sprite <use> in the inspector, the Brand kit button and page, a picture has an address, thumbnails served at the size they are drawn.
• The toolkit and the skills — brand-kit, clone-prototype padding a glyph crop before tracing, refkit shoot --scale as a float.
• Example canvases — tiktok-ios, x-ios, instagram-ios, perplexity-ios, and brand kits on thirteen canvases.

No code changes. This is the line each of those pull requests owed the file.

Version is 1.3.0, not a patch: CONTRIBUTING says minor is "a new skill, a new refkit subcommand, a canvas feature". This window has a new skill and canvas features. images rows in layout.json are additive, so not a major.

Does not bump the version. After this merges:

1. Actions → Release → 1.3.0 (must dispatch from main; the workflow refuses a branch).

2. On release/1.3.0, the same edit as release 1.2.0 #72: leave ## Unreleased as the placeholder, insert ## v1.3.0 under it with this lede, so the grouped bullets fall under that heading:

   ## v1.3.0
   
   YYYY-MM-DD. A product's published brand sits on the canvas next to its screens, as
   pictures you can link to, and the board you inspect is the one on the canvas
   rather than a copy in the panel. A fourth skill collects those pictures. Four
   more example canvases.
   

   The tag job reads exactly ## v1.3.0. Merging without that heading falls back to generated notes.

3. Merge. The tag super-prototyping--v1.3.0 and the GitHub Release follow.

Checklist

• No ref-*.html, assets/refs/ or other third-party captures are in this PR.
• If a canvas folder changed: gen.py was edited and re-run, and the NN-*.html boards were not hand-edited.
• If a canvas folder changed: layout.json, probes.json, crops.json and assets.json are committed alongside the boards.
• Every new canvas folder has a README.md and no folder has its own .gitignore.
• If a user would see this change: it has a line under ## Unreleased in RELEASE-NOTES.md.
• If canvas/ changed: bun test and bun run build pass in canvas/.

Gates run locally on current main (this PR is notes only):

• canvas/: oxlint, 95 tests, build
• tools/: 25 refkit + 6 sp-canvas checks
• scripts/bump-version.sh --check: all 7 files at 1.2.0
• claude plugin validate . --strict and .claude-plugin/plugin.json --strict: passed

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