btcindexer: update insertBlockInfo to return proper status

[robert-zaremba]

The function should return a proper status rather than boolean.

Context : https://github.com/gonative-cc/workers/pull/213/files#diff-9851882ca208cd20b739824885fad0c3f5703eecd9eb3492cbdd34b6785a8b84R69

[robert-zaremba]

Idea:

// 1. Prepare a check to see if the row already exists
const checkStmt = this.d1.prepare(
    `SELECT 1 FROM btc_blocks WHERE height = ? AND network = ?`
);

// 2. Prepare your existing Upsert statement
const insertStmt = this.d1.prepare(
    `INSERT INTO btc_blocks (hash, height, network, inserted_at) VALUES (?, ?, ?, ?)
     ON CONFLICT(height, network) DO UPDATE SET
       hash = excluded.hash,
       inserted_at = excluded.inserted_at,
       is_scanned = 0
     WHERE btc_blocks.hash IS NOT excluded.hash AND excluded.inserted_at > btc_blocks.inserted_at`
);

// 3. Execute both in a single batch
// 'batch' ensures they run sequentially and saves network round-trips
const [checkResult, upsertResult] = await this.d1.batch([
    checkStmt.bind(b.height, b.network),
    insertStmt.bind(b.hash, b.height, b.network, b.timestamp_ms)
]);

// 4. Determine exactly what happened
const wasFound = checkResult.results.length > 0;
const rowsChanged = upsertResult.meta.changes > 0;

if (!wasFound) {
    return { status: 'inserted', changed: true };
} else if (rowsChanged) {
    return { status: 'updated', changed: true }; // Found, but hash changed so we updated
} else {
    return { status: 'skipped', changed: false }; // Found, but hash was identical (or timestamp older)
}