feat(repos): multi-machine path support via host_paths

Adds a JSONB column `host_paths` to managed_repos mapping
hostname → absolute local path. Fixes the consistency-checker
failure when the same repo lives at different paths on different
machines (e.g. /home/worsch/marki-docx on the workstation vs
/home/tegwick/marki-docx on custodiancore).

Changes:
- Migration g4b5c6d7e8f9: adds host_paths JSONB (default {})
- Model: host_paths Mapped[dict] column
- Schemas: host_paths in RepoRead; new RepoPathRegister schema
- Router: POST /repos/{slug}/paths/ — merges one host entry
- consistency_check.py: resolve_repo_path() prefers host_paths
  [hostname] over local_path; --repo-path CLI override added
- MCP: update_repo_path(slug, path, host?) tool
- Makefile: register-path target; REPO_PATH passthrough on
  check-consistency and fix-consistency targets
- TOOLS.md: documents update_repo_path

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

state-hub/mcp_server/server.py

@@ -971,6 +971,27 @@ def register_repo(
     return json.dumps(repo, indent=2)
 
 
+@mcp.tool()
+def update_repo_path(repo_slug: str, path: str, host: str | None = None) -> str:
+    """Register or update the local filesystem path for a repo on a specific host.
+
+    Use this when a repo lives at a different absolute path on different machines
+    (e.g. /home/worsch/marki-docx on the workstation vs /home/tegwick/marki-docx
+    on custodiancore). The consistency checker will prefer the host-specific path
+    over the legacy local_path field.
+
+    Args:
+        repo_slug: Managed-repo slug (e.g. 'marki-docx')
+        path: Absolute local path on the target machine (e.g. '/home/tegwick/marki-docx')
+        host: Hostname to register the path for. Defaults to the current machine's hostname.
+    """
+    import socket as _socket
+    if not host:
+        host = _socket.gethostname()
+    repo = _post(f"/repos/{repo_slug}/paths", {"host": host, "path": path})
+    return json.dumps(repo, indent=2)
+
+
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