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

README.md

@@ -61,8 +61,8 @@ Minimal `flake.nix` for a host that runs hive-c0re:
       modules = [
         hyperhive.nixosModules.default  # hive-c0re + hive-forge in one import
         ({ ... }: {
-          services.hive-c0re.enable = true;
-          # services.hive-c0re.operatorPronouns = "they/them";  # default: "she/her"
+          hyperhive.enable = true;
+          # hyperhive.c0re.operatorPronouns = "they/them";  # default: "she/her"
 
           # ... rest of your host config
           system.stateVersion = "25.11";
@@ -78,7 +78,7 @@ manager container, and auto-rebuilds any container whose hyperhive
 rev goes stale. `claude-code` is unfree — hyperhive scopes the
 whitelist to itself, nothing for the operator to set.
 
-Optional: set `services.hive-c0re.preBuildAgentTemplates = true;`
+Optional: set `hyperhive.c0re.preBuildAgentTemplates = true;`
 to pre-fetch the per-container system closures into your host's
 /nix/store as part of `nixos-rebuild`. First-agent-spawn then
 completes in seconds instead of minutes (no nixpkgs/claude-code