refactor(vdb): move importable modules into vdb/ package (compat shims)
Step 7a (incremental). Builds on !6 (merged)–!10 (merged). Groundwork for an installable, on-PATH vdb.
Relocates the modules the CLI imports — vdb_config, vdb_cli, vdb_resolve, vdb_indexdata, vdb_gitdata, vdb_backupdata, vdb_ignoredata, vdb_viewers, vault_notify (+ feature-catalog.yaml) — from scripts/ and the repo root into vdb/. Once they live in the package, the future wheel no longer needs a scripts/ sibling at runtime.
Old paths keep thin compat shims that re-export the real module and copy its names, so bare-name import X and importlib-by-path loads both keep working (tests, scripts/vdb-menu.py, migrate-config.py, the mcp server's sibling import). vdb_cli + vdb/cli.py switch to package-relative imports.
vdb_config.HERE moves with it: CATALOG_PATH = HERE/feature-catalog.yaml (now in vdb/), SCHEMA_DIR/REPO_ROOT = HERE.parent still resolve to repo root.
test_vault_notify read back module-global state that load() mutates (a shim copy can't proxy that) → now imports the real vdb.vault_notify. Full suite green; standalone indexer/mcp/menu/migrate and python -m vdb all verified.