refactor: move hive-c0re options to hyperhive namespace (#612)

- Move options.services.hive-c0re → options.hyperhive.c0re
- Add options.hyperhive.enable to auto-enable c0re + subsystems
- Add deprecation alias for services.hive-c0re.enable (backward compat)
- Update doc references in README, flake.nix, docs, harness-base.nix
- Simplifies config: 'hyperhive.enable = true' now enables everything

Existing operator configs using services.hive-c0re.enable will
continue to work but emit a deprecation warning. Aligns the option
namespace with the existing hyperhive.* family (matrix, forge, domain).

fixes #612

nix/templates/harness-base.nix

@@ -36,7 +36,7 @@
       `"haiku"`, `"sonnet"`, `"opus"` (or any future identifier). Context
       window sizes are looked up at runtime from the
       `HIVE_CONTEXT_WINDOW_TOKENS_<KEY_UPPER>` env vars injected by the
-      meta flake; override sizes via `services.hive-c0re.contextWindowTokens`
+      meta flake; override sizes via `hyperhive.c0re.contextWindowTokens`
       on the host.
     '';
   };
@@ -595,7 +595,7 @@
     # both the harness binary and any user-shell `cargo run` inside the
     # container resolve them from the same path.
     # HIVE_CONTEXT_WINDOW_TOKENS_* are injected by the meta flake from the
-    # host-level `services.hive-c0re.contextWindowTokens` option — not set here.
+    # host-level `hyperhive.c0re.contextWindowTokens` option — not set here.
     environment.variables = {
       HIVE_DEFAULT_MODEL = config.hyperhive.model;
       HIVE_ASSETS_DIR = "${pkgs.hyperhive-assets}/share/hyperhive";