feat: consolidate reviewed Diagram Design 2.6.0 release (#134)

* fix(commands): stop hardcoding the visual-type count

Integrates the final reviewed diff from PR #112.

* docs(high-level): correct effective width checklist

Integrates the final reviewed diff from PR #105.

* fix(commands): quote profile argument hint

Integrates the final reviewed diff from PR #126.

* test(sankey): gate conservation and ribbon geometry

Integrates the final reviewed diff from PR #103.

* feat(tooling): add doctor diagnostics gate

Integrates the final reviewed diff from PR #132.

* feat(scripts): lint diagrams as rendered

Integrates the final reviewed diff from PR #18.

* feat(types): add quantitative polar chart

Integrates the final reviewed diff from PR #101.

* chore(release): consolidate reviewed changes in 2.6.0

Documents every combined gate and synchronizes Claude, Codex, and Factory metadata for the 39-type release.

* fix(doctor): support installed-skill projects

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Co-authored-by: mysoniw <soniw1@gmail.com>
Co-authored-by: thang <76550342+thangldw@users.noreply.github.com>
Co-authored-by: YinShaokun <yinshaokun@didiglobal.com>
Co-authored-by: 0xDarkMatter <0xDarkMatter@users.noreply.github.com>
Co-authored-by: Rupam Pal <rupam.pal@euromonitor.com>
Co-authored-by: Yuvraj3905 <yuvraj202001@gmail.com>

commands/import-drawio.md

@@ -22,7 +22,8 @@ Accepts `.drawio`, `.drawio.xml`, `.xml`, `.drawio.png`, and `.drawio.svg`.
 - `--detail=balanced` · `--audience=mixed`.
 - `--variant=light` — the minimal light template.
 - A single-page file selects its only page; a multi-page file lists pages and asks which to use.
-- Type is chosen from the extracted structure; `--type` forces one of the 38.
+- Type is chosen from the extracted structure; `--type` forces one of the visual types in
+  [`SKILL.md` §3](../skills/diagram-design/SKILL.md).
 
 ## Flags