Exempt lsp from startup auto-index; serve lightweight zk.list selects…

… from FindMinimalNotes

- main.go: skip quiet full re-index for the long-lived lsp command
  (was stalling first request ~7s on large notebooks); extracted
  needsAutoIndex helper with unit test.
- internal/adapter/lsp/cmd_list.go: fast path for selects needing only
  filename/filenameStem/path/absPath/title/metadata via FindMinimalNotes,
  falling back to FindNotes otherwise.
- Tests: selectionNeedsFull light/heavy routing, minimal-vs-full render
  equivalence, needsAutoIndex exemptions.