docs: add 30-day expiry callout + ship 4 auto-save tools

Adds a brief [!IMPORTANT] callout at the top of the README pointing
users to the urgent announcement at #1388. Claude Code auto-deletes
local JSONL transcripts after 30 days; users without the auto-save
hooks wired are losing transcript data off the rolling window.

Ships 4 small standalone tools at tools/:
- backup_claude_jsonls.sh — rsync ~/.claude/projects/ to a safe folder
- render_jsonl.py — convert JSONL transcripts to readable text
- find_orphan_claude_jsonls.sh — scan backup locations for orphan
  Claude Code transcripts (multi-line shape detection + topic preview)
- save.md — Claude Code slash command for manual /save into MemPalace

Tools verified by independent agent against v3.3.4 source.
Read-only on user data. POSIX bash + Python stdlib only.

tools/render_jsonl.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+"""render_jsonl.py — turn one Claude Code JSONL transcript into readable text.
+
+Claude Code stores conversations at ~/.claude/projects/<proj>/<uuid>.jsonl and
+Anthropic auto-deletes them after 30 days
+(https://docs.claude.com/en/docs/claude-code/data-usage). This script renders a
+JSONL into a clean .txt so you can keep / read / share it without the tooling.
+
+Usage:
+    python3 render_jsonl.py <input.jsonl> [output.txt]
+
+Stdlib only. Python 3.9+. Read-only on the input.
+"""
+import json, sys
+from pathlib import Path
+
+def extract_text(content):
+    if isinstance(content, str):
+        return content.strip()
+    if isinstance(content, list):
+        parts = []
+        for blk in content:
+            if isinstance(blk, dict) and blk.get("type") == "text":
+                t = (blk.get("text") or "").strip()
+                if t:
+                    parts.append(t)
+        return "\n".join(parts)
+    return ""
+
+def main():
+    if len(sys.argv) < 2:
+        print(__doc__); sys.exit(1)
+    src = Path(sys.argv[1])
+    if not src.is_file():
+        print(f"ERROR: not a file: {src}"); sys.exit(1)
+    out = open(sys.argv[2], "w", encoding="utf-8") if len(sys.argv) > 2 else sys.stdout
+
+    turns, stamps = [], []
+    for raw in src.read_text(encoding="utf-8", errors="replace").splitlines():
+        if not raw.strip():
+            continue
+        try:
+            obj = json.loads(raw)
+        except json.JSONDecodeError:
+            continue
+        role = obj.get("type") or (obj.get("message") or {}).get("role")
+        if role not in ("user", "assistant"):
+            continue
+        msg = obj.get("message") or obj
+        text = extract_text(msg.get("content"))
+        if not text:
+            continue
+        ts = obj.get("timestamp") or ""
+        if ts: stamps.append(ts)
+        turns.append((ts, role, text))
+
+    header = [
+        f"# Claude Code transcript: {src}",
+        f"# Total turns: {len(turns)}",
+        f"# Date range : {min(stamps) if stamps else 'n/a'}  ->  {max(stamps) if stamps else 'n/a'}",
+        "#" + "-" * 70, "",
+    ]
+    out.write("\n".join(header))
+    for ts, role, text in turns:
+        out.write(f"\n[{ts}] {role.upper()}\n{text}\n\n{'-'*72}\n")
+    if out is not sys.stdout:
+        out.close()
+        print(f"Wrote {len(turns)} turns to {sys.argv[2]}")
+
+if __name__ == "__main__":
+    main()