feat: add transaction hash search to blockchain explorer and cleanup settlement storage

Blockchain Explorer:
- Add transaction hash search support (64-char hex pattern validation)
- Fetch and display transaction details in modal (hash, type, from/to, amount, fee, block)
- Fix regex escape sequence in block height validation
- Update search placeholder text to mention both search types
- Add blank lines between function definitions for PEP 8 compliance

Settlement Storage:
- Add timedelta import for future

scripts/dev/ws_load_test.py

@@ -1,54 +0,0 @@
-from __future__ import annotations
-
-import asyncio
-import json
-from contextlib import asynccontextmanager
-from typing import List
-
-import websockets
-
-DEFAULT_WS_URL = "ws://127.0.0.1:8000/rpc/ws"
-BLOCK_TOPIC = "/blocks"
-TRANSACTION_TOPIC = "/transactions"
-
-
-async def producer(ws_url: str, interval: float = 0.1, total: int = 100) -> None:
-    async with websockets.connect(f"{ws_url}{BLOCK_TOPIC}") as websocket:
-        for index in range(total):
-            payload = {
-                "height": index,
-                "hash": f"0x{index:064x}",
-                "parent_hash": f"0x{index-1:064x}",
-                "timestamp": "2025-01-01T00:00:00Z",
-                "tx_count": 0,
-            }
-            await websocket.send(json.dumps(payload))
-            await asyncio.sleep(interval)
-
-
-async def consumer(name: str, ws_url: str, path: str, duration: float = 5.0) -> None:
-    async with websockets.connect(f"{ws_url}{path}") as websocket:
-        end = asyncio.get_event_loop().time() + duration
-        received = 0
-        while asyncio.get_event_loop().time() < end:
-            try:
-                message = await asyncio.wait_for(websocket.recv(), timeout=1.0)
-            except asyncio.TimeoutError:
-                continue
-            received += 1
-            if received % 10 == 0:
-                print(f"[{name}] received {received} messages")
-        print(f"[{name}] total received: {received}")
-
-
-async def main() -> None:
-    ws_url = DEFAULT_WS_URL
-    consumers = [
-        consumer("blocks-consumer", ws_url, BLOCK_TOPIC),
-        consumer("tx-consumer", ws_url, TRANSACTION_TOPIC),
-    ]
-    await asyncio.gather(producer(ws_url), *consumers)
-
-
-if __name__ == "__main__":
-    asyncio.run(main())