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/composition/src/build.rs

@@ -2,8 +2,9 @@ use application::auth::deps::{
     LoginDeps, LogoutDeps, RefreshDeps, RegisterAndLoginDeps, RegisterDeps,
 };
 use application::deps::{
-    AuthGroup, Deps, DiaryGroup, GoalsGroup, ImportGroup, IntegrationsGroup, MoviesGroup,
-    PersonGroup, SearchGroup, SocialGroup, UsersGroup, WatchlistGroup, WorkerDeps, WrapupGroup,
+    AuthGroup, Deps, DiaryGroup, GoalsGroup, ImportGroup, InsightsGroup, IntegrationsGroup,
+    MoviesGroup, PersonGroup, SearchGroup, SocialGroup, UsersGroup, WatchlistGroup, WorkerDeps,
+    WrapupGroup,
 };
 use application::diary::deps::{
     DeleteReviewDeps, EditReviewDeps, ExportDiaryDeps, GetActivityFeedDeps, GetDiaryDeps,
@@ -15,6 +16,7 @@ use application::import::deps::{
     DeleteImportProfileDeps, ExecuteImportDeps, GetMappingStageDeps, GetPreviewStageDeps,
     GetSessionStateDeps, ListImportProfilesDeps, SaveProfileDeps,
 };
+use application::insights::deps::GetInsightsDeps;
 use application::integrations::deps::{
     ConfirmWatchEventsDeps, DismissWatchEventsDeps, GenerateWebhookTokenDeps, GetWatchQueueDeps,
     GetWebhookTokensDeps, IngestWatchEventDeps, RevokeWebhookTokenDeps,
@@ -175,6 +177,11 @@ pub fn build_deps(
                 import_profile: repos.import_profile.clone(),
             },
         },
+        insights: InsightsGroup {
+            get: GetInsightsDeps {
+                insights: repos.insights.clone(),
+            },
+        },
         integrations: IntegrationsGroup {
             ingest_watch_event: IngestWatchEventDeps {
                 webhook_token: repos.webhook_token.clone(),