feat(timeline): upgrade seed phase to hybrid search

Replace FTS-only seed entity discovery with hybrid search (FTS + vector
via RRF), using the same search_hybrid infrastructure as the search
command. Falls back gracefully to FTS-only when Ollama is unavailable.

Changes:
- seed_timeline() now accepts OllamaClient, delegates to search_hybrid
- New resolve_documents_to_entities() replaces find_seed_entities()
- SeedResult gains search_mode field tracking actual mode used
- TimelineResult carries search_mode through to JSON renderer
- run_timeline wires up OllamaClient from config
- handle_timeline made async for the hybrid search await
- Tests updated for new function signatures

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main.rs

@@ -179,7 +179,9 @@ async fn main() {
         Some(Commands::Search(args)) => {
             handle_search(cli.config.as_deref(), args, robot_mode).await
         }
-        Some(Commands::Timeline(args)) => handle_timeline(cli.config.as_deref(), args, robot_mode),
+        Some(Commands::Timeline(args)) => {
+            handle_timeline(cli.config.as_deref(), args, robot_mode).await
+        }
         Some(Commands::Who(args)) => handle_who(cli.config.as_deref(), args, robot_mode),
         Some(Commands::Drift {
             entity_type,
@@ -1763,7 +1765,7 @@ async fn handle_stats(
     Ok(())
 }
 
-fn handle_timeline(
+async fn handle_timeline(
     config_override: Option<&str>,
     args: TimelineArgs,
     robot_mode: bool,
@@ -1784,7 +1786,7 @@ fn handle_timeline(
         max_evidence: args.max_evidence,
     };
 
-    let result = run_timeline(&config, &params)?;
+    let result = run_timeline(&config, &params).await?;
 
     if robot_mode {
         print_timeline_json_with_meta(