Remove find_context_files — identity comes from memory nodes

Deleted the directory-walking CLAUDE.md/POC.md loader. Identity now
comes entirely from personality_nodes in the memory graph.

Simplified:
- assemble_context_message() takes just personality_nodes
- Removed config_file_count/memory_file_count tracking
- reload_for_model() → reload_context() (no longer model-specific)

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

src/agent/mod.rs

@@ -579,7 +579,7 @@ impl Agent {
     }
 
     pub async fn compact(&self) {
-        match crate::config::reload_for_model(&self.app_config, &self.prompt_file).await {
+        match crate::config::reload_context().await {
             Ok(personality) => {
                 let mut ctx = self.context.lock().await;
                 // System section (prompt + tools) set by new(), don't touch it