Fix context budgeting and compaction

- Budget now counts exact message tokens matching what assemble_api_messages
  sends, not raw string content. Eliminates undercounting from formatting
  overhead (journal headers, personality separators, working stack).

- Load journal before trimming so trim accounts for journal cost.

- Compact before every turn, not just after turn completion. Prevents
  agent_cycle surfaced memories from pushing context over budget.

- Move agent_cycle orchestration from Agent::turn to Mind::start_turn —
  surfaced memories and reflections now precede the user message.

- Move AgentCycleState from Agent to Mind — it's orchestration, not
  per-agent state. memory_scoring_in_flight and memory_scores stay on
  Agent where they belong.

- Tag DMN entries as ConversationEntry::Dmn — compaction evicts them
  first since they're ephemeral. Compaction also prefers evicting
  memories over conversation when memories exceed 50% of entry tokens.

- Kill /retry slash command.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/user/mod.rs

@@ -316,7 +316,6 @@ pub async fn run(
     mind_tx: tokio::sync::mpsc::UnboundedSender<MindCommand>,
 ) -> Result<()> {
     let agent = &mind.agent;
-    let shared_mind = &mind.shared;
     // UI-owned state
     let mut idle_state = crate::thalamus::idle::State::new();
     idle_state.load();