Rename Castle -> Wild PC across the repo

Repo-side rename only (Phases 1-3 of the migration plan); the live box
(~/.castle, systemd units, /data/castle, domains) is a separate cutover.

- Slug `castle` -> `wildpc`: CLI command, module names (wildpc_core/cli/api),
  dist names, entry point `wildpc = wildpc_cli.main:main`.
- Identifiers: CastleConfig/NATSClient/DirError/MDNS -> Wildpc*.
- Env/constants: CASTLE_* -> WILDPC_*; ~/.castle -> ~/.wildpc, castle.yaml ->
  wildpc.yaml, /data/castle -> /data/wildpc.
- Systemd UNIT_PREFIX castle- -> wildpc-; own programs castle-api/gateway/etc.
- Display prose "Castle" -> "Wild PC" in docs, agent-guide files, README, frontend.
- Package dirs and bootstrap yaml renamed via git mv; lockfiles regenerated;
  redundant nested uv.lock files dropped (workspace root lock is authoritative).

Tests: core 273, cli 47, wildpc-api 120 all pass. Frontend type-checks + builds.
Fixed a stale test fixture (secret_env_path kind arg) broken pre-rename.

core/tests/test_deploy_prune.py

@@ -5,9 +5,9 @@ from __future__ import annotations
 from pathlib import Path
 from unittest.mock import patch
 
-from castle_core import deploy as deploy_mod
-from castle_core.deploy import _desired_unit_files, _prune_orphans
-from castle_core.registry import Deployment, NodeConfig, NodeRegistry
+from wildpc_core import deploy as deploy_mod
+from wildpc_core.deploy import _desired_unit_files, _prune_orphans
+from wildpc_core.registry import Deployment, NodeConfig, NodeRegistry
 
 
 def _svc(managed: bool = True, schedule: str | None = None) -> Deployment:
@@ -23,7 +23,7 @@ def _svc(managed: bool = True, schedule: str | None = None) -> Deployment:
 
 
 def _registry(**deployed: Deployment) -> NodeRegistry:
-    reg = NodeRegistry(node=NodeConfig(castle_root="/x", gateway_port=9000))
+    reg = NodeRegistry(node=NodeConfig(wildpc_root="/x", gateway_port=9000))
     for name, d in deployed.items():
         d.name = name
         reg.put(d)
@@ -38,11 +38,11 @@ def _touch(d: Path, *names: str) -> None:
 class TestDesiredUnitFiles:
     def test_managed_service_yields_service_file(self) -> None:
         reg = _registry(foo=_svc())
-        assert _desired_unit_files(reg) == {"castle-foo.service"}
+        assert _desired_unit_files(reg) == {"wildpc-foo.service"}
 
     def test_scheduled_job_yields_service_and_timer(self) -> None:
         reg = _registry(job=_svc(schedule="0 2 * * *"))
-        assert _desired_unit_files(reg) == {"castle-job-job.service", "castle-job-job.timer"}
+        assert _desired_unit_files(reg) == {"wildpc-job-job.service", "wildpc-job-job.timer"}
 
     def test_unmanaged_excluded(self) -> None:
         reg = _registry(foo=_svc(managed=False))
@@ -54,7 +54,7 @@ class TestPruneOrphans:
         units = tmp_path / "systemd"
         units.mkdir()
         # keep-me is in the registry; gone is not; gone.timer is also orphaned
-        _touch(units, "castle-keep.service", "castle-gone.service", "castle-gone.timer")
+        _touch(units, "wildpc-keep.service", "wildpc-gone.service", "wildpc-gone.timer")
         reg = _registry(keep=_svc())
         msgs: list[str] = []
         with (
@@ -62,17 +62,17 @@ class TestPruneOrphans:
             patch.object(deploy_mod.subprocess, "run") as mock_run,
         ):
             _prune_orphans(reg, msgs)
-        assert (units / "castle-keep.service").exists()
-        assert not (units / "castle-gone.service").exists()
-        assert not (units / "castle-gone.timer").exists()
+        assert (units / "wildpc-keep.service").exists()
+        assert not (units / "wildpc-gone.service").exists()
+        assert not (units / "wildpc-gone.timer").exists()
         # stop + disable were invoked for each removed unit
         assert mock_run.call_count >= 2
-        assert any("castle-gone.service" in m for m in msgs)
+        assert any("wildpc-gone.service" in m for m in msgs)
 
     def test_unscheduled_job_drops_stale_timer_keeps_service(self, tmp_path: Path) -> None:
         units = tmp_path / "systemd"
         units.mkdir()
-        _touch(units, "castle-job.service", "castle-job.timer")
+        _touch(units, "wildpc-job.service", "wildpc-job.timer")
         # job is still managed but no longer scheduled → its timer is now an orphan
         reg = _registry(job=_svc(schedule=None))
         with (
@@ -80,17 +80,17 @@ class TestPruneOrphans:
             patch.object(deploy_mod.subprocess, "run"),
         ):
             _prune_orphans(reg, [])
-        assert (units / "castle-job.service").exists()
-        assert not (units / "castle-job.timer").exists()
+        assert (units / "wildpc-job.service").exists()
+        assert not (units / "wildpc-job.timer").exists()
 
     def test_demoted_to_unmanaged_is_pruned(self, tmp_path: Path) -> None:
         units = tmp_path / "systemd"
         units.mkdir()
-        _touch(units, "castle-foo.service")
+        _touch(units, "wildpc-foo.service")
         reg = _registry(foo=_svc(managed=False))  # still in registry but unmanaged
         with (
             patch.object(deploy_mod, "SYSTEMD_USER_DIR", units),
             patch.object(deploy_mod.subprocess, "run"),
         ):
             _prune_orphans(reg, [])
-        assert not (units / "castle-foo.service").exists()
+        assert not (units / "wildpc-foo.service").exists()