Resolved toward the branch: PM provisions uv/python (main's install.ps1 uv-shim
salvage + its test and workflow steps dropped), the shim re-exec stays retired,
package.json carries no electron-builder block (afterExtract identity stamp wired
into electron-builder.config.cjs instead; after-pack.mjs keeps signing only),
Desktop workspace-deps helpers stay retired. Main's scratch-dir bootstrap
(export_scratch_tmp_env) is taken and re-run after profile resolution.
e1576d06a6