Add optimistic concurrency and reactive SQLite clients

[TheFellow]

Summary

• add store-owned revision tokens and atomic compare-and-swap update/delete semantics, including migration of existing rows
• round-trip revisions through mutable domain models and CLI/GUI/TUI editors so stale saves return typed conflicts
• add a coalesced PRAGMA data_version monitor and wire GUI/TUI invalidation through normal authorized queries
• preserve dirty workflows, refresh cached views when safe, and discard out-of-order async reloads
• document the consistency and notification contract

Validation

• go generate ./...
• go build ./...
• go tool arch-lint -config=.arch-lint.yaml
• GOTOOLCHAIN=go1.26.5 go run github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2 run
• go test -race -shuffle=on -count=1 -timeout=5m ./...