release(slice4): v0.50.0 — single-entry metadata edit + sidecar-aware writes (§22.4a SLICE-4)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

SPEC.md

@@ -5152,6 +5152,16 @@ never used for routing or lookup. New entries are never assigned one.
 > across collections. What `type` still selects is the **terminology** (item 2,
 > the entry noun, shipped v0.45.0) and the **default `initial_state` / review
 > posture** (§22.4b–c).
+>
+> **Shipped status.** The design lands incrementally: sidecar storage +
+> dual-read (SLICE-1, v0.47.0), the collection `fields:` schema + central
+> validation (SLICE-2, v0.48.0), faceted left-pane filtering (SLICE-3, v0.49.0),
+> and **single-entry metadata edit (SLICE-4, v0.50.0)** — the direct-commit
+> `POST …/rfcs/{slug}/meta` editor (contributor+, validated at the write
+> boundary), the schema-driven detail panel, all entry **write paths made
+> sidecar-aware** (a migrated body-only `.md` never re-grows frontmatter), and
+> the Owner-gated `POST …/collections/{cid}/migrate` endpoint. Bulk edit
+> (SLICE-5) follows. See §9.5 for the edit-metadata write-through this reuses.
 
 Every collection declares a `type` in its `.collection.yaml` manifest
 (§22.2), chosen at creation and **immutable**: one of `document`,