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/src/operator.rs

@@ -21,7 +21,7 @@ use color_eyre::Result;
 use color_eyre::eyre::{bail, eyre};
 use serde::Deserialize;
 
-use omnigraph_server::config::ReadOutputFormat;
+use crate::read_format::{ReadOutputFormat, TableCellLayout};
 
 pub(crate) const OPERATOR_HOME_ENV: &str = "OMNIGRAPH_HOME";
 pub(crate) const OPERATOR_DIR: &str = ".omnigraph";
@@ -102,10 +102,9 @@ pub(crate) struct OperatorIdentity {
 pub(crate) struct OperatorDefaults {
     /// Default read output format, below every more-specific source.
     pub(crate) output: Option<ReadOutputFormat>,
-    /// Table rendering preferences (below the legacy cli.table_* keys
-    /// during the RFC-008 window).
+    /// Table rendering preferences for `--format table`.
     pub(crate) table_max_column_width: Option<usize>,
-    pub(crate) table_cell_layout: Option<omnigraph_server::config::TableCellLayout>,
+    pub(crate) table_cell_layout: Option<TableCellLayout>,
     /// Default server scope (RFC-011): the everyday addressing when no
     /// `--profile` / primitive / legacy address is given. Names an entry
     /// under `servers:`. Mutually exclusive with `store` — a scope binds one