feat(ui): add /dash route, shared nav, project dashboard with /v1/projects API

Restructure routes: / and /dash show a project overview dashboard,
/activity hosts the existing timeline, /cv remains. Shared Layout
component provides consistent nav header and footer across all routes.

New /v1/projects endpoint aggregates per-repo activity stats (commits,
issues, PRs, date range) from existing event data via SQL. Dashboard
ranks projects by weighted recency + volume score and renders a card
grid.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/moments-api/src/main.rs

@@ -11,7 +11,7 @@ use chrono::{DateTime, Utc};
 use clap::Parser;
 use moments_core::{EventReader, reshape};
 use moments_data::PgStore;
-use moments_entities::{EventQuery, Source, SourceSummary, TimelineItem};
+use moments_entities::{EventQuery, ProjectSummary, Source, SourceSummary, TimelineItem};
 use serde::Deserialize;
 use tower_http::{cors::CorsLayer, trace::TraceLayer};
 use tracing::info;
@@ -50,6 +50,7 @@ async fn main() -> anyhow::Result<()> {
         .route("/v1/healthz", get(healthz))
         .route("/v1/events", get(list_events))
         .route("/v1/sources", get(list_sources))
+        .route("/v1/projects", get(list_projects))
         .with_state(state)
         .layer(TraceLayer::new_for_http())
         .layer(CorsLayer::permissive());
@@ -122,6 +123,13 @@ async fn list_sources(
     Ok(Json(summaries))
 }
 
+async fn list_projects(
+    State(state): State<AppState>,
+) -> Result<Json<Vec<ProjectSummary>>, ApiError> {
+    let projects = state.store.list_projects().await.map_err(internal)?;
+    Ok(Json(projects))
+}
+
 fn parse_sources(raw: &str) -> Result<Vec<Source>, ApiError> {
     raw.split(',')
         .map(str::trim)