feat!: delete the legacy OmnigraphConfig + config migrate; finish the omnigraph.yaml docs sweep (#252)

* refactor(cli): own ReadOutputFormat/TableCellLayout in the CLI

The two output-presentation enums lived in `omnigraph-server::config` and were
re-exported for the CLI, even though the server never used them. Move both
definitions into `omnigraph-cli/src/read_format.rs` (where the renderer already
lives) and drop them from the server's public re-export. This is a step toward
deleting the legacy `omnigraph-server::config` module entirely — a CLI
presentation concern has no business in the server crate.

No behavior change. The server keeps private copies in `config.rs` only for the
soon-to-be-deleted legacy `CliDefaults`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* feat(cli)!: remove the `config migrate` command and migrate.rs

`config migrate` was the last CLI consumer of the legacy `omnigraph.yaml`
(`OmnigraphConfig` + `load_config`). With the excision complete there is no
legacy file to split, so the whole `omnigraph config` command group is removed
along with `migrate.rs`. The `OmnigraphConfig` type, `load_config`, and the
deprecation machinery are deleted next.

- Remove `Command::Config` / `ConfigCommand` from the clap surface and the
  dispatch arm; drop `mod migrate;` and the now-unused `load_config` import.
- Drop the `Command::Config` arms in `planes.rs`.
- Delete the `config_migrate_splits_legacy_config` integration test.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* feat(server)!: delete the legacy OmnigraphConfig type and load_config

With `config migrate` gone, nothing loads `omnigraph.yaml` anymore. Delete the
entire `omnigraph-server::config` module: the `OmnigraphConfig` type and its
sub-structs (`ProjectConfig`, `TargetConfig`, `CliDefaults`, `ServerDefaults`,
`AuthDefaults`, `QueryDefaults`, `AliasConfig`, `AliasCommand`, `PolicySettings`,
`QueryEntry`, `McpSettings`), `load_config`, and the RFC-008 deprecation
machinery (`OMNIGRAPH_CONFIG`, `OMNIGRAPH_NO_LEGACY_CONFIG`,
`OMNIGRAPH_SUPPRESS_YAML_DEPRECATION`, the deprecation map + warner).

- `QueryRegistry::load` (the only `OmnigraphConfig`/`QueryEntry` consumer; its
  only caller was its own test) is removed — server boot and the CLI both build
  registries via `QueryRegistry::from_specs`.
- `graph_resource_id_for_selection` (CLI-only) moves into the CLI
  (`helpers.rs`), with its unit test; the server no longer exports it.
- Drop the already-dead `format_registry_load_errors` helper (config-adjacent).

No behavior change — every deleted item was unreachable after the excision.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* docs: purge the legacy omnigraph.yaml surface from the docs

Finish the RFC-011 excision in the docs: the CLI no longer reads omnigraph.yaml
and the server boots cluster-only, so every doc that described the legacy file
as a live config is now wrong.

- AGENTS.md: rewrite the HTTP-server line to cluster-only boot (drop the
  single-graph/flat-route and omnigraph.yaml-boot framing); rewrite the CLI
  two-surface-config passage (drop `config migrate`, the deprecation env vars,
  and "Never extend omnigraph.yaml"); fix the topic table + capability rows.
- cli/reference.md: delete the entire "omnigraph.yaml schema (legacy combined
  file)" section and the `config migrate` row; re-home the `policy` row, the
  bearer-token chain, the actor/format/param-precedence references, and the
  `--config` mentions to the operator config + `--cluster`.
- cli/index.md: rewrite the multi-graph-server + add-graph paragraphs to
  cluster (`--cluster` + `cluster apply`); fix the policy examples to
  `--cluster`; replace the `## Config` omnigraph.yaml example with the
  operator/cluster two-surface model.
- operations/policy.md: rewrite per-graph-vs-server-level policy to the cluster
  `policies:`/`applies_to` model; re-home the actor + CLI tooling sections.
- clusters/config.md, clusters/index.md, deployment.md: server boots from the
  cluster only; per-operator facts come from ~/.omnigraph/config.yaml.
- architecture.md, testing.md: drop the stale omnigraph.yaml / deleted-test
  references.

RFCs, design specs, and prior release notes are left as historical records.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

crates/omnigraph-cli/tests/cli_schema_config.rs

@@ -562,74 +562,3 @@ fn graphs_list_against_local_uri_errors_with_remote_only_message() {
     );
 }
 
-/// RFC-008 stage 2: `config migrate` proposes the split read-only, applies
-/// it with --write (operator merge never clobbers; cluster.yaml emitted),
-/// and a second --write is idempotent.
-#[test]
-fn config_migrate_splits_legacy_config() {
-    let temp = tempdir().unwrap();
-    fs::write(
-        temp.path().join("omnigraph.yaml"),
-        "graphs:\n  prod:\n    uri: https://graph.example.com\n    bearer_token_env: PROD_TOKEN\ncli:\n  actor: act-me\n  output_format: json\npolicy:\n  file: ./top.policy.yaml\n",
-    )
-    .unwrap();
-    let operator_home = tempfile::tempdir().unwrap();
-    fs::write(
-        operator_home.path().join("config.yaml"),
-        "operator:\n  actor: act-existing\n",
-    )
-    .unwrap();
-
-    // Read-only proposal: names both halves, writes nothing.
-    let output = cli()
-        .current_dir(temp.path())
-        .env("OMNIGRAPH_HOME", operator_home.path())
-        .env("OMNIGRAPH_SUPPRESS_YAML_DEPRECATION", "1")
-        .arg("config")
-        .arg("migrate")
-        .output()
-        .unwrap();
-    assert!(output.status.success(), "{output:?}");
-    let stdout = String::from_utf8_lossy(&output.stdout);
-    assert!(stdout.contains("team half -> cluster.yaml"), "{stdout}");
-    assert!(stdout.contains("operator.actor: act-me"), "{stdout}");
-    assert!(stdout.contains("omnigraph login prod"), "{stdout}");
-    assert!(!temp.path().join("cluster.yaml").exists());
-
-    // --write: cluster.yaml lands; the existing operator actor is KEPT.
-    let output = cli()
-        .current_dir(temp.path())
-        .env("OMNIGRAPH_HOME", operator_home.path())
-        .env("OMNIGRAPH_SUPPRESS_YAML_DEPRECATION", "1")
-        .arg("config")
-        .arg("migrate")
-        .arg("--write")
-        .output()
-        .unwrap();
-    assert!(output.status.success(), "{output:?}");
-    let cluster = fs::read_to_string(temp.path().join("cluster.yaml")).unwrap();
-    assert!(cluster.contains("version: 1") && cluster.contains("  prod:"), "{cluster}");
-    let operator_text =
-        fs::read_to_string(operator_home.path().join("config.yaml")).unwrap();
-    assert!(operator_text.contains("act-existing"), "{operator_text}");
-    assert!(!operator_text.contains("act-me"), "existing keys win: {operator_text}");
-    assert!(operator_text.contains("output: json"), "{operator_text}");
-    assert!(
-        operator_text.contains("url: https://graph.example.com"),
-        "{operator_text}"
-    );
-
-    // Second --write: cluster.yaml exists -> proposal file, no clobber.
-    let output = cli()
-        .current_dir(temp.path())
-        .env("OMNIGRAPH_HOME", operator_home.path())
-        .env("OMNIGRAPH_SUPPRESS_YAML_DEPRECATION", "1")
-        .arg("config")
-        .arg("migrate")
-        .arg("--write")
-        .output()
-        .unwrap();
-    assert!(output.status.success(), "{output:?}");
-    assert!(temp.path().join("cluster.yaml.proposed").exists());
-}
-