Add resource create and migrate commands

## Changes

- Add `flowmcp resource create <schema-path>` command for file-based DB creation
- Add `flowmcp resource migrate` command for old-format schema migration
- Add `--basis` global flag for configurable basis folder
- Add better-sqlite3 dependency

## Tests
- 473 tests pass (12 new tests added)

## Source
PRD-14 from `flowmcp-resources-and-prompts-evolution-v0.3.md`