future-plans: add kv-store shared library and delta tracking

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

future-plans.md

@@ -1,5 +1,18 @@
 # Future Plans
 
+## KV store
+
+### Extract into shared library
+`kv-store.mjs` is already copied into at least 3 projects (`electronics-inventory`,
+`fs-views`, `publication-tool`). Should live in its own Gitea repo as an installable
+npm package (`npm install git+https://...`) so changes propagate rather than drift.
+
+### Delta / revision tracking
+Add a delta log alongside the main snapshot file (e.g. `inventory.ndjson.deltas`)
+that records every `set`/`delete` as a timestamped entry. The main file stays a
+clean current-state snapshot; the delta file accumulates the full history. Enables
+undo, audit trails, and debugging data corruption.
+
 ## App architecture
 
 ### parse_url mutates too many module-level variables