Add read_file skill, session persistence, and update script

- New read_file skill: paginated file reading with line ranges,
  path restricted to /workspace, binary detection, directory listing
- Session persistence via SQLite + FTS5: conversation history survives
  agent restarts, last N messages restored into deque on boot,
  auto-prune to 1000 messages
- Update truncation hint to reference read_file instead of run_command
- New scripts/update.sh for patching rootfs + rebuilding snapshot

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/update.sh

@@ -0,0 +1,81 @@
+#!/bin/bash
+# Update fireclaw agent code and skills in the rootfs.
+# Stops the overseer, patches the rootfs, rebuilds snapshot, restarts.
+#
+# Usage: ./scripts/update.sh
+
+set -euo pipefail
+
+log()  { echo -e "\033[1;34m[fireclaw]\033[0m $*"; }
+step() { echo -e "\n\033[1;32m━━━ $* ━━━\033[0m"; }
+ok()   { echo -e "  \033[0;32m✓\033[0m $*"; }
+err()  { echo -e "\033[1;31m[error]\033[0m $*" >&2; exit 1; }
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+FIRECLAW_DIR="$HOME/.fireclaw"
+ROOTFS="$FIRECLAW_DIR/agent-rootfs.ext4"
+MNT="/tmp/fireclaw-update-mnt"
+
+[[ ! -f "$ROOTFS" ]] && err "No rootfs found at $ROOTFS — run install.sh first."
+
+# ─── Stop overseer ──────────────────────────────────────────────────
+
+step "Stop overseer"
+if systemctl is-active --quiet fireclaw-overseer 2>/dev/null; then
+    sudo systemctl stop fireclaw-overseer
+    ok "Overseer stopped"
+else
+    ok "Overseer not running"
+fi
+
+# Wait for any firecracker processes to exit
+sleep 1
+
+# ─── Build TypeScript ───────────────────────────────────────────────
+
+step "Build TypeScript"
+cd "$SCRIPT_DIR"
+npm run build
+ok "TypeScript compiled"
+
+# ─── Patch rootfs ───────────────────────────────────────────────────
+
+step "Patch rootfs"
+
+sudo mkdir -p "$MNT"
+sudo mount "$ROOTFS" "$MNT" || err "Failed to mount rootfs"
+
+trap 'sudo umount "$MNT" 2>/dev/null; sudo rmdir "$MNT" 2>/dev/null' EXIT
+
+sudo cp "$SCRIPT_DIR/agent/"*.py "$MNT/opt/agent/"
+sudo chmod +x "$MNT/opt/agent/agent.py"
+
+sudo rm -rf "$MNT/opt/skills/"*
+sudo cp -r "$SCRIPT_DIR/skills/"* "$MNT/opt/skills/"
+sudo chmod +x "$MNT/opt/skills/"*/run.*
+
+sudo umount "$MNT"
+sudo rmdir "$MNT"
+trap - EXIT
+
+ok "Agent + skills updated in rootfs"
+
+# ─── Rebuild snapshot ───────────────────────────────────────────────
+
+step "Rebuild snapshot"
+
+rm -f "$FIRECLAW_DIR/snapshot.state" \
+      "$FIRECLAW_DIR/snapshot.mem" \
+      "$FIRECLAW_DIR/snapshot-rootfs.ext4"
+
+fireclaw snapshot create
+ok "Snapshot rebuilt"
+
+# ─── Restart overseer ──────────────────────────────────────────────
+
+step "Restart overseer"
+sudo systemctl start fireclaw-overseer
+ok "Overseer started"
+
+echo ""
+log "Update complete. Use IRC to test."