Core never read or emitted the manifest `feedpak_version` field. Adopt it:
- sloppak.py: `FEEDPAK_VERSION = "1.2.0"` constant (the format version this build
targets); `LoadedSloppak.feedpak_version` read from the manifest on load
(string, else None for legacy/absent).
- Stamp the version on the two core manifest-rewrite paths, without downgrading
an existing (possibly higher) declared version:
- gp2notation: `setdefault` before its notation-add rewrite.
- songmeta: opportunistically when a metadata field is supplied (gated on the
existing `dirty` flag, so never a standalone rewrite).
Core has no create-from-scratch path (RS-free repo) — the editor plugin's
create-mode save stamping FEEDPAK_VERSION is a follow-up in that repo. Internal
"sloppak" naming is intentionally left as-is (a rename is out of scope / risky).
Codex-reviewed: no P1/P2. +6 tests (read present/absent/non-string; metadata-write
stamp-when-absent / preserve-existing / no-op-no-stamp) + updated the gp2notation
key-order test for the appended version. 197 sloppak/songmeta/gp2notation tests pass.
Closes#527. Part of got-feedback/feedback#334.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
