feat: always-on Insights — correlation analysis over viewing habits

Conservative, live insights (ADR-0010) derived from each user's diary:
rating lift by genre (first-time watches only), genre seasonality vs a
uniform 1/12 month baseline, medium weekend-lift, and watch-time rhythm.

- domain: WatchRow model, InsightsQuery port, pure insights_analyzer with
  all honesty thresholds (sample minimums, strength cutoffs, suppressions
  for import noise), unit-tested
- adapters: thin Sqlite/Postgres fetch twins, reusing WrapUp's genre fetch
- application: get_insights use case, InsightsGroup in Deps
- composition/server: wiring through Repositories/DatabaseOutput
- presentation: GET /api/v1/insights handler, typed serde-tagged DTOs,
  openapi doc
- spa: /insights route (shadcn cards), insights feature hook, profile
  entry link, en locale strings
- server test: end-to-end seed sqlite → HTTP → rating lift + rhythm

Also records ADR-0010, defines "Insight" in the glossary, and includes
pre-existing worktree comment-stripping cleanups.

crates/application/src/users/authorize_admin.rs

@@ -5,15 +5,6 @@ use uuid::Uuid;
 
 use crate::users::deps::AuthorizeAdminDeps;
 
-/// Whether `user_id` is an admin, for the two extractors (`AdminApiUser`,
-/// `AdminUser`) that gate admin-only routes.
-///
-/// Returns `Ok(None)` when the user row does not exist — a distinct success
-/// value, not folded into `DomainError::NotFound`, specifically so callers can
-/// tell "row missing" apart from "repository call failed" without depending on
-/// which `DomainError` variant a lookup failure happens to produce. Each
-/// extractor rejects those two cases differently (missing row is a 401/404,
-/// a repository error is a 500) and that distinction must stay exact.
 pub async fn execute(
     deps: &AuthorizeAdminDeps,
     user_id: Uuid,