# 008 — Settings model

## Summary

Implement the single, process-wide settings model described in the README's NavMenu
section: colour scheme, CSS path config, and the settings file location — settable
via CLI args, persisted at a sensible default OS location.

## Scope

- A `Settings` struct: colour scheme choice, list of imported/linked CSS entries
  (see [010](010-css-management.md)), and whatever else profiles need to hang off of.
- Default settings file location using an OS-conventions crate (e.g. `directories`)
  rather than a hardcoded path.
- `clap` arg(s) to override the settings file path at runtime (extend the existing
  `Args` in `main.rs`, which today only has `--port`/`--static-dir`).
- Load-on-start / save-on-change semantics; "at runtime, there is only 1 settings" —
  i.e. a single in-memory settings instance, not per-request state, analogous to how
  the engine owns the index.
- Settings "owns" the profiles per the README — this ticket only needs to define
  where profiles live under settings, not implement profile CRUD itself (that's
  [009](009-presets-profiles.md)).

## Acceptance criteria

- Running with no args creates/reads a settings file at the documented default
  location.
- `--settings-path` (or similar) overrides it.
- Settings persist across restarts (edit, restart, re-read matches).

## Depends on

None.