Refactor plugin version lookup to use afero and fix shadowing bug in Run

[vzhang-stripe]

It's annoying to run the local.build.dev version when developing a plugin, update the CLI version preference to always run the local version

What

• Extracts "local.build.dev" into a localDevelopmentVersion constant
• Introduces lookUpInstalledVersion() method that checks for a local dev build first, then falls back to a semver glob — using afero.Fs instead of filepath.Glob so it's testable
• Adds isLocalDevelopmentVersion() predicate and uses it to skip checksum verification for local dev builds in both verifyChecksum and Run
• Fixes a variable shadowing bug in Run where := inside the else block created a new inner version, leaving the outer variable empty and causing getPluginInstallPath / getChecksum to
  receive "" for all non-dev plugin invocations

No regression for production users

Regular users never have a local.build.dev directory, so lookUpInstalledVersion always falls through to the semver glob. afero.OsFs wraps the real filesystem, so behavior is identical to the
previous filepath.Glob call. The checksum skip only fires for the local.build.dev version string.

Tests

• TestVerifyChecksumSkipsLocalDevelopmentVersion — checksum is skipped for local dev builds
• TestLookUpInstalledVersionPrefersLocalDevelopmentVersion — local dev dir takes priority over an installed release
• TestLookUpInstalledVersionFallsBackToInstalledRelease — falls back to semver glob when no local dev build exists

[vcheung-stripe]

Nice!