refactor!: retire wails.json, config.yml is the version source

- version.go (generated, never hand-edited) carries the compiled-in
  version; app.go drops the wails.json embed plus the gjson dependency
- make release bumps config.yml and regenerates version.go in one
  commit; the re-run-safe guards from the 1.99.1 cycle carry over
- release guard reads config.yml; CI CLI pin and cache key move to
  beta.22 to match the lockstep above
- release wrapper and config NOTE comments updated; deletion proof:
  wails3 build green plus a dev boot reaching the connected state
  with the file absent (the one cold-boot failure reproduced as a
  Vite 8 cold-start vs app retry race, cleared by rerunning warm)

build/config.yml

@@ -1,5 +1,6 @@
 # Wails v3 project configuration.
-# NOTE: `make release` bumps `info.version` below alongside wails.json.
+# NOTE: `info.version` below is the single version source: `make release`
+# bumps it and regenerates version.go (the compiled-in copy) from it.
 # Never touch the top-level `version: '3'` — that is the config file schema,
 # not the app version.
 version: '3'