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>

api/models/managed_repo.py

@@ -2,7 +2,7 @@ import uuid
 from datetime import datetime
 
 from sqlalchemy import DateTime, ForeignKey, String, Text
-from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.dialects.postgresql import JSONB, UUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from api.models.base import Base, TimestampMixin, new_uuid
@@ -20,6 +20,7 @@ class ManagedRepo(Base, TimestampMixin):
     slug: Mapped[str] = mapped_column(String(100), unique=True, nullable=False, index=True)
     name: Mapped[str] = mapped_column(String(200), nullable=False)
     local_path: Mapped[str | None] = mapped_column(Text, nullable=True)
+    host_paths: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict, server_default="{}")
     remote_url: Mapped[str | None] = mapped_column(Text, nullable=True)
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
     status: Mapped[str] = mapped_column(String(20), nullable=False, default="active")