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/deps.rs

@@ -13,6 +13,7 @@ use crate::import::deps::{
     DeleteImportProfileDeps, ExecuteImportDeps, GetMappingStageDeps, GetPreviewStageDeps,
     GetSessionStateDeps, ListImportProfilesDeps, SaveProfileDeps,
 };
+use crate::insights::deps::GetInsightsDeps;
 use crate::integrations::deps::{
     ConfirmWatchEventsDeps, DismissWatchEventsDeps, GenerateWebhookTokenDeps, GetWatchQueueDeps,
     GetWebhookTokensDeps, IngestWatchEventDeps, RevokeWebhookTokenDeps,
@@ -92,6 +93,10 @@ pub struct IntegrationsGroup {
     pub plex_parser: Arc<dyn MediaServerParser>,
 }
 
+pub struct InsightsGroup {
+    pub get: GetInsightsDeps,
+}
+
 pub struct MoviesGroup {
     pub sync_poster: SyncPosterDeps,
     pub get_movie_profile: GetMovieProfileDeps,
@@ -159,6 +164,7 @@ pub struct Deps {
     pub diary: DiaryGroup,
     pub goals: GoalsGroup,
     pub import: ImportGroup,
+    pub insights: InsightsGroup,
     pub integrations: IntegrationsGroup,
     pub movies: MoviesGroup,
     pub person: PersonGroup,