fix(workspace,filesystem,sync): annotate implicit any parameters across production files

[braden-w]

Why

The three packages had 45 implicit any parameters scattered across production files. These accumulated because the tsconfigs don't always resolve external module types (Yjs, lib0, etc.), so callback parameter types can't be inferred. This PR annotates all of them in one pass—zero TS7006 errors remain in production files.

What changed

14 files, net +49 lines. All changes are type annotations only—zero behavior changes.

workspace (23 params, 9 files)

Fix	Files
Yjs observe callbacks (Y.YArrayEvent, Y.Transaction, Y.Item)	y-keyvalue.ts, y-keyvalue-lww.ts
Y.Map forEach iterators	sheet.ts, timeline.ts
Y.XmlFragment children	timeline.ts
Schema validator params	schema-union.ts, standard-schema.ts
Catch-clause-style params → unknown	websocket.ts, datetime-string.ts, y-keyvalue-lww.ts, y-keyvalue.ts
Markdown file filter callback	prepare-markdown-files.ts

filesystem (13 params, 4 files)

Fix	Files
POSIX method path: string params	file-system.ts
Y.Map forEach iterators	formats/markdown.ts
Table observer changedIds: ReadonlySet<string>	tree/path-index.ts
SQLite row shape + change set types	extensions/sqlite-index/index.ts

sync (9 params, 1 file)

Fix	Files
lib0 encoder: encoding.Encoder callbacks	protocol.ts

Follows the same pattern as PR #1690 which fixed 8 type errors in workspace production files.