Replaces gopkg.in/yaml.v3 with github.com/BurntSushi/toml. Updates
struct tags, default config path, Dockerfile CMD, README, and ships
config.example.toml in place of the YAML example. ${ENV_VAR}
expansion still runs on the raw file before parsing, so the behavior
is unchanged.
Adds internal/arr with a shared HTTP layer and per-service clients that
look up candidates and POST the chosen one back with monitored=true and
search-on-add enabled. Lidarr requires metadata_profile_id, now part of
ArrConfig and validated when lidarr is set.
Pivot from FastAPI web portal to a Matrix command bot (modeled on Pete).
Users will issue !movie / !tv / !music commands in allowlisted rooms; the
bot performs a top-hit search against Radarr/Sonarr/Lidarr and adds it.
This commit is session 1 of a multi-session rewrite (see SESSION_PLAN.md):
- Delete app/, requirements.txt, old Dockerfile, .env.example
- Add go.mod (mautrix-go + yaml.v3)
- Add internal/config: YAML loader with ${ENV} expansion, validates
matrix creds, allowed_rooms, and per-service *arr config
- Reset .gitignore / .dockerignore for the Go layout
