feat(db): backfill, DB-backed web scans, firewall snapshot view (R001/S001/F001)

- R001: app/db/backfill.py imports git-history blocklist -> ledger, firewall
  snapshots, and per-source requests.csv (idempotent; ran live migrating 705
  historical blocklist entries).
- S001: web_scan.latest_scans() now merges SQLite 'scans' records so the
  dashboard surfaces CLI/restart scans (_db_scans).
- F001: /api/firewall/snapshots + 'Snapshot history' panel; added
  recent_firewall_snapshots() query with entry counts.

app/db/backfill.py

@@ -0,0 +1,196 @@
+#!/usr/bin/env python3
+"""R001 — one-time backfill of legacy runtime data into the SQLite store.
+
+Imports existing JSON/CSV/git-history data so the DB becomes the authoritative
+source without losing anything already accumulated on a deployed instance:
+
+- cumulative blocklist from the git-history reconstruction (old source of
+  truth) -> ``blocklist_entries`` (grow-only ledger)
+- firewall snapshots from ``data/mikrotik/*.json`` -> ``firewall_snapshots``
+- per-source requests from ``reports/<source>/data/requests.csv`` (best effort)
+
+Idempotent: skips rows already present. Safe to run repeatedly.
+
+Usage:
+    python -m app.db.backfill [--dry-run]
+"""
+
+from __future__ import annotations
+
+import argparse
+import csv
+import json
+import os
+import sys
+from datetime import datetime, timezone
+
+from ..utils.constants import (
+    APP_REPORT_DATA_DIR,
+    DATA_DIR,
+    MIKROTIK_DATA_DIR,
+    NPM_REPORT_DIR,
+    COPYPARTY_REPORT_DIR,
+)
+
+
+def utcnow() -> str:
+    return datetime.now(timezone.utc).isoformat(timespec="seconds")
+
+
+def _read_cidr_lines(path: str) -> set[str]:
+    try:
+        with open(path, "r", encoding="utf-8") as f:
+            return {line.strip() for line in f if line.strip()}
+    except OSError:
+        return set()
+
+
+def backfill_blocklist(conn, dry_run: bool = False) -> dict:
+    """Import the legacy cumulative blocklist into the ledger."""
+    from . import repositories as repo
+    from ..utils.blocklist_history import (
+        committed_lines, current_file_lines,
+    )
+
+    v4_path = os.path.join(APP_REPORT_DATA_DIR, "blocklist_ipv4.txt")
+    v6_path = os.path.join(APP_REPORT_DATA_DIR, "blocklist_ipv6.txt")
+    # Legacy source of truth: union of all git revisions + working file +
+    # (there is no earlier scan target to add here).
+    complete_v4 = committed_lines(v4_path) | current_file_lines(v4_path)
+    complete_v6 = committed_lines(v6_path) | current_file_lines(v6_path)
+    cidrs = sorted(complete_v4 | complete_v6)
+    if not cidrs:
+        return {"blocklist": {"cidrs": 0, "added": 0}}
+    if dry_run:
+        return {"blocklist": {"cidrs": len(cidrs), "added": None, "dry_run": True}}
+    result = repo.record_blocklist(conn, cidrs, added_by="backfill")
+    return {"blocklist": result}
+
+
+def backfill_firewall(conn, dry_run: bool = False) -> dict:
+    """Import the latest firewall snapshot from ``data/mikrotik/*.json``."""
+    from . import repositories as repo
+
+    def _load(name: str) -> list:
+        try:
+            with open(os.path.join(MIKROTIK_DATA_DIR, name), "r",
+                      encoding="utf-8") as f:
+                data = json.load(f)
+            return data if isinstance(data, list) else []
+        except (OSError, ValueError):
+            return []
+
+    addr_v4 = _load("address_list_ipv4.json")
+    addr_v6 = _load("address_list_ipv6.json")
+    fw_v4 = _load("firewall_ipv4.json")
+    fw_v6 = _load("firewall_ipv6.json")
+    if not (addr_v4 or addr_v6 or fw_v4 or fw_v6):
+        return {"firewall": {"dry_run": dry_run, "snapshot": None}}
+    # Idempotent: if a firewall snapshot already exists (previous backfill),
+    # don't create another copy of the same latest state.
+    n = conn.execute(
+        "SELECT COUNT(*) FROM firewall_snapshots").fetchone()[0]
+    if n:
+        return {"firewall": {"dry_run": dry_run, "snapshot": "exists",
+                              "skipped": True}}
+    if dry_run:
+        return {"firewall": {"dry_run": True, "snapshot": None}}
+    sid = repo.save_firewall_snapshot(
+        conn, address_lists_v4=addr_v4, address_lists_v6=addr_v6,
+        rules_v4=fw_v4, rules_v6=fw_v6)
+    return {"firewall": {"snapshot": sid}}
+
+
+def backfill_requests(conn, dry_run: bool = False) -> dict:
+    """Best-effort import of per-source ``requests.csv`` files.
+
+    Only ingests rows that don't already exist (keyed on source+log_file+ts+ip).
+    Legacy CSV columns vary by source; we keep a conservative mapping and never
+    fail the whole backfill over a single bad file.
+    """
+    from . import repositories as repo
+
+    seen = set()
+    for r in conn.execute(
+            "SELECT source, log_file, ts, ip FROM requests"):
+        seen.add((r["source"], r["log_file"], r["ts"], r["ip"]))
+
+    candidates = [
+        (os.path.join(COPYPARTY_REPORT_DIR, "data", "requests.csv"), "copyparty"),
+        (os.path.join(NPM_REPORT_DIR, "data", "requests.csv"), "npm"),
+    ]
+    total = 0
+    for path, source in candidates:
+        if not os.path.exists(path):
+            continue
+        try:
+            with open(path, "r", encoding="utf-8", errors="replace") as f:
+                reader = csv.DictReader(f)
+                rows = []
+                for row in reader:
+                    ip = (row.get("ip") or "").strip()
+                    ts = row.get("ts") or row.get("timestamp") or ""
+                    log_file = row.get("log_file") or row.get("file") or ""
+                    if not ip:
+                        continue
+                    key = (source, log_file, ts, ip)
+                    if key in seen:
+                        continue
+                    seen.add(key)
+                    rows.append({
+                        "source": source, "scan_id": None, "log_file": log_file,
+                        "ts": ts, "ip": ip,
+                        "version": 4 if ":" not in ip else 6,
+                        "method": row.get("method"), "path": row.get("path"),
+                        "status": _int_or_none(row.get("status")),
+                        "upstream_status": _int_or_none(
+                            row.get("upstream_status")),
+                        "host": row.get("host"), "user": row.get("user"),
+                        "ua": row.get("ua") or row.get("user_agent"),
+                        "referer": row.get("referer"),
+                        "denied": _bool_str(row.get("denied")),
+                        "banned": _bool_str(row.get("banned")),
+                        "is_error": _bool_str(row.get("is_error")),
+                        "extra": None,
+                    })
+                    total += 1
+            if not dry_run and total:
+                repo.insert_requests(conn, rows)
+        except Exception as exc:
+            print(f"  WARN: requests.csv backfill {source}: {exc}")
+    return {"requests": {"imported": total, "dry_run": dry_run}}
+
+
+def _int_or_none(v):
+    try:
+        if v in (None, "", "-"):
+            return None
+        return int(v)
+    except (TypeError, ValueError):
+        return None
+
+
+def _bool_str(v):
+    if isinstance(v, str):
+        return int(v.strip().lower() in ("1", "true", "yes", "t"))
+    return int(bool(v))
+
+
+def main(argv: list[str] | None = None) -> None:
+    p = argparse.ArgumentParser(prog="python -m app.db.backfill",
+                                description="Backfill legacy runtime data into SQLite.")
+    p.add_argument("--dry-run", action="store_true",
+                   help="report what would be imported without writing")
+    opts = p.parse_args(argv)
+
+    from . import get_connection
+    conn = get_connection()
+    print(f"== backfill (dry_run={opts.dry_run}) ==")
+    print("blocklist:", backfill_blocklist(conn, dry_run=opts.dry_run))
+    print("firewall :", backfill_firewall(conn, dry_run=opts.dry_run))
+    print("requests :", backfill_requests(conn, dry_run=opts.dry_run))
+    print("== done ==")
+
+
+if __name__ == "__main__":
+    sys.exit(main())