fix: Validate SENTRY_RELEASE environment variable

[szokeasaurusrex]

Apply the same validation to SENTRY_RELEASE that we also apply to the --release argument.

Fixes #2444
Fixes CLI-7

---

Note

Validate SENTRY_RELEASE with the same rules as --release and refactor release validation/parsing for clap.

• Config (src/config.rs):
  • Validate SENTRY_RELEASE via args::validate_release; ignore with warning if invalid; require release if missing.
• CLI Args (src/utils/args.rs):
  • Refactor release validation: expose validate_release returning anyhow::Result<()> and add parse_release for clap.
  • Use parse_release for --release and --version value parsers.

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[linear]

CLI-7 Validate release strings locally

[lcian]

LGTM