Address reviewer feedback (Cursor + cubic) on PR #60

All eight comments verified against source and applied:

- AGENTS.md: pull @docs/{invariants,lance,testing}.md imports out of
  the markdown blockquote. Claude Code's @-import parser expects @ at
  column 0; the leading "> " of a blockquote silently broke
  recognition, so the claimed auto-include did nothing. (Cursor,
  Medium severity.)
- docs/cli-reference.md: command-family count 13 → 17. The current
  enum Command in crates/omnigraph-cli/src/main.rs has 17 top-level
  variants. (cubic P2.)
- docs/ci.md: Homebrew tap update is a regular `git push`, not a
  force-push (release.yml:117 is `git push origin HEAD:main`). (cubic
  P2.)
- docs/errors.md: add the Storage variant to the NanoError list — it
  exists at error.rs:88-89 but the doc enumerated only 10 of 11.
  (cubic P2.)
- docs/storage.md: clarify tombstone semantics. There is no
  tombstone_version column; state.rs:180 reads the tombstone version
  from the table_version column on rows where object_type =
  table_tombstone. (cubic P2.)
- docs/branches-commits.md: split the GraphCommit pseudo-struct from
  the underlying storage. actor_id is joined in-memory from
  _graph_commit_actors.lance, not a column on _graph_commits.lance.
  (cubic P2.)
- docs/schema-language.md: rename IR_VERSION to SCHEMA_IR_VERSION to
  match the actual constant name in catalog/schema_ir.rs:11.
  (cubic P3.)
- docs/testing.md: engine integration test count 16 → 15 (matches
  `ls crates/omnigraph/tests/*.rs`). (cubic P3.)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/cli-reference.md

@@ -2,7 +2,7 @@
 
 A reference for the `omnigraph` binary's command surface and `omnigraph.yaml` schema. For a quick-start guide, see [cli.md](cli.md).
 
-13 top-level command families, 40+ subcommands. All commands accept either a positional `URI`, `--uri`, or a `--target <name>` resolved against `omnigraph.yaml`.
+17 top-level command families, 40+ subcommands. All commands accept either a positional `URI`, `--uri`, or a `--target <name>` resolved against `omnigraph.yaml`.
 
 ## Top-level commands