fix(release): preserve the full annotated tag message

[GSTJ]

Summary

Preserves the complete annotated release-tag message and adds the generated v1.5.0-rc4 changelog entry.

Details

• Pipes the rendered message into git tag -F -, avoiding Bash command substitution that removed its final newline.
• Keeps --cleanup=verbatim, so Markdown headings remain intact.
• Leaves the published rc4 tag immutable; the corrected behavior starts with the next tag.

Verification

• A local annotated tag and the generator output match byte for byte at 288 bytes each.
• pnpm changelog regenerates the committed changelog entry.
• bash -n, ShellCheck, and Python byte-compilation pass for the release scripts.
• Format, lint, typecheck, and all 79 tests pass locally.

[GSTJ]

Local annotated-tag byte proof: