chore(openspec): drop 9 superseded proposals + 11 stub archive files

Drop 9 batch proposals that are superseded by the boocode-lift-analysis
(boocontext-audit, conductor upgrades, self-healing/verify-gate skills):
add-3tier-memory, import-llm-evaluator, import-pregel-engine, plugin-platform,
conductor-evolution, code-intelligence-upgrade, dev-workflow, ui-overhaul,
agent-reliability.

Delete 11 stub archive files (49-66B each, 'Status: Shipped. Archived.' only)
that provide zero documentation value over the existing CHANGELOG.md + git tags.

openspec/changes/add-behavioral-engine/specs/audit-middleware/spec.md

@@ -0,0 +1,21 @@
+## ADDED Requirements
+
+### Requirement: PostToolUse audit logging
+- **WHEN** a tool is used
+- **THEN** the tool name, input summary, and timestamp are appended to the JSONL audit buffer
+
+### Requirement: Stop hook flush
+- **WHEN** a response completes
+- **THEN** the audit buffer is flushed to the session audit trail and index is updated
+
+### Requirement: UserPromptSubmit context injection
+- **WHEN** a user message is submitted
+- **THEN** session context (session ID, record count, critical alerts) is injected into the prompt
+
+### Requirement: Anomaly detection
+- **WHEN** audit records are checked against alert rules
+- **THEN** anomalies at CRITICAL level are injected into the context
+
+#### Scenario: Full audit trail
+- **WHEN** an agent runs 10 tool calls across 3 turns
+- **THEN** the audit trail contains 10 JSONL records, a session summary, and an updated index