#10 release view/list drop unknown-field warnings

Repro: write .forge/releases/vW1.md with frontmatter field zzz: 1, run f0rge release view vW1 / release list. No warning on stderr. issue.rs warn() emits per-field warnings plus schema note; release.rs only calls warn_schema. Expect: same warning shape as issue (one line per unknown field on stderr, exit 0). Scope: cmd/release.rs (append_hashes, load_all, view).