Set up repo scaffolding: gitignore, AGENTS.md, Phase 0 doc

- .gitignore matching sibling repos (target/, node_modules/, .worktrees/, Cargo.lock)
- AGENTS.md on the alkcall/alksocks template: git workflow, 17 project
  conventions adapted for a virtual-filesystem crate (no forced host-FS
  access, metadata/content split, durability ordering, storage-trait
  one-way doors), verification commands (docs-only posture for Phase 0),
  and architecture context pointing at the ancestor research and family ADRs
- docs/research/phase-0.md: initial Phase 0 draft — vision/scope sketch,
  guiding principles, what's already settled, prior art (alknet-filesystem
  POCs, iroh-blobs + external-store probe, git/git-lfs, alkgit backend
  seam, russh-sftp, SQLite/honker, rudolfs), 15 open questions
  (OQ-FS-01..15) grouped by theme, a 7-entry candidate POC register
  (proposals, none run), survey list, and an unconverged checklist

Verification: docs-only repo — every referenced path, ADR id, and OQ id
checked to exist (workspace paths, alkcall ADRs 034-051, alkgit research
files); OQ numbering OQ-FS-01..15 complete with no gaps

.gitignore

@@ -0,0 +1,4 @@
+target/
+node_modules/
+.worktrees/
+Cargo.lock