Move all instance state into ~/.castle/ with clear separation:
- code/ — user project source (was components/)
- artifacts/ — generated specs, built content (was generated/, static/)
- data/ — service runtime data (was /data/castle/)
- secrets/ — credentials
castle.yaml moves to ~/.castle/castle.yaml as the canonical location.
Source paths use repo: prefix for git repo programs (castle-api, app)
and relative paths for user projects (code/central-context).
Add idempotent install.sh for bootstrapping infrastructure (Docker,
Caddy, MQTT, Postgres, Neo4j) with interactive service detection.
Remove components/ from repo (now in ~/.castle/code/), deinit
submodules, remove .gitmodules.
