sentry-cli v3→v4 codemod: authToken shorthand and execute→run edge cases

Trap 1: { authToken } shorthand — renaming key authToken→token while leaving shorthand=true produces { token } referencing a nonexistent binding. Fix: when shorthand=true and key is authToken, disable shorthand and emit token: authToken. Trap 2: execute([...]) → run(...) passes raw v3 argv tokens (e.g. releases, new) verbatim; v4 command paths differ (releases→release, new→create). Fix: insert // TODO(sentry-v4) comment before the rewritten call reminding the user to remap command names. Trap 3: --header shim overwrites SENTRY_CUSTOM_HEADERS on each iteration. Fix: accumulate into semicolon-separated string; assign once after loop. v4 format: "Name: Value; Name2: Value2".