journal tools: use NodeType instead of string key matching

- journal_new: create EpisodicSession node with auto-generated key
- journal_tail: query by node_type, not by parsing a monolithic node
- journal_update: find latest EpisodicSession by timestamp
- No string key matching anywhere — all typed
- Fixes journal entries not appearing in 'poc-memory journal tail'
- Also: added --provenance/-p filter to 'poc-memory tail'
- Also: fix early return in surface_observe_cycle store load failure
- Also: scale max_turns by number of steps (50 per step)

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

src/subconscious/api.rs

@@ -57,7 +57,7 @@ pub async fn call_api_with_tools(
     let mut next_prompt_idx = 1; // index of next prompt to inject
     let reasoning = crate::config::get().api_reasoning.clone();
 
-    let max_turns = 50;
+    let max_turns = 50 * prompts.len();
     for turn in 0..max_turns {
         log(&format!("\n=== TURN {} ({} messages) ===\n", turn, messages.len()));