feat(core): broker summaries from IPOT

Adds a BrokerSummaryProvider capability served by Indo Premier's public
broker summary page: the top 10 buyers and sellers of a stock by lots over
a date range, with totals. No login or key.

- api/ipot: pure parser (decimal scaling of `1.6 M`-style figures), a
  client that retries the server's spurious 404s, and a fixture mock.
- broker: Broker::summary/latest over the cache (7 days for closed ranges,
  5 minutes for today), range checks, and IDX member names bundled from
  GetBrokerCodeList.
- foreign_net_value is null for filtered summaries: the source does not
  apply the filters to it.

The endpoint's behavior was first mapped by fzn0x/idx (MIT).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V3syn2fN2LNo5pvTSqc6eh

crates/idx-core/src/api/ipot/mod.rs

@@ -0,0 +1,101 @@
+//! Indo Premier Sekuritas (IPOT) broker summary: which brokers bought and
+//! sold a stock. No login or key.
+//!
+//! `GET https://www.indopremier.com/module/saham/include/data-brokersummary.php`
+//! `?code=BBCA&start=MM/DD/YYYY&end=MM/DD/YYYY&fd=all|F|D&board=all|RG|TN|NG`
+//! answers an HTML fragment with the top 10 buyers and the top 10 sellers,
+//! ranked by lots, and totals for the range. Figures of a million and more
+//! are abbreviated to one decimal (`1.6 M`). A range without trades gives
+//! blank rows and zero totals; an unknown code gives `Invalid stock code!`
+//! with HTTP 200. The endpoint's behavior was first mapped by fzn0x/idx
+//! (MIT).
+
+mod client;
+pub mod parse;
+
+use client::IpotClient;
+pub use parse::{BrokerSummaryRaw, IpotPage, parse_broker_summary, parse_figure};
+
+use super::BrokerSummaryProvider;
+use crate::broker::types::{BrokerBoard, BrokerInvestor, BrokerQuery};
+use crate::error::IdxError;
+
+const ENDPOINT: &str = "https://www.indopremier.com/module/saham/include/data-brokersummary.php";
+
+/// The request URL for `code` (a bare IDX code such as `BBCA`).
+pub fn broker_summary_url(code: &str, query: &BrokerQuery) -> String {
+    let investor = match query.investor {
+        BrokerInvestor::All => "all",
+        BrokerInvestor::Foreign => "F",
+        BrokerInvestor::Domestic => "D",
+    };
+    let board = match query.board {
+        BrokerBoard::All => "all",
+        BrokerBoard::Regular => "RG",
+        BrokerBoard::Cash => "TN",
+        BrokerBoard::Negotiated => "NG",
+    };
+    format!(
+        "{ENDPOINT}?code={code}&start={}&end={}&fd={investor}&board={board}",
+        query.from.format("%m/%d/%Y"),
+        query.to.format("%m/%d/%Y"),
+    )
+}
+
+/// A parsed page as a summary; an unknown code is `SymbolNotFound`.
+pub(crate) fn summary_from_html(code: &str, html: &str) -> Result<BrokerSummaryRaw, IdxError> {
+    match parse_broker_summary(html)? {
+        IpotPage::Invalid => Err(IdxError::SymbolNotFound(code.to_string())),
+        IpotPage::Summary(raw) => Ok(raw),
+    }
+}
+
+pub struct IpotProvider {
+    client: IpotClient,
+}
+
+impl IpotProvider {
+    pub fn new() -> Self {
+        Self {
+            client: IpotClient::new(),
+        }
+    }
+}
+
+impl Default for IpotProvider {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl BrokerSummaryProvider for IpotProvider {
+    fn broker_summary(
+        &self,
+        code: &str,
+        query: &BrokerQuery,
+    ) -> Result<BrokerSummaryRaw, IdxError> {
+        let html = self.client.fetch_html(&broker_summary_url(code, query))?;
+        summary_from_html(code, &html)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use chrono::NaiveDate;
+
+    use super::*;
+
+    #[test]
+    fn test_broker_summary_url_maps_filters_to_source_codes() {
+        let query = BrokerQuery {
+            from: NaiveDate::from_ymd_opt(2026, 10, 12).unwrap(),
+            to: NaiveDate::from_ymd_opt(2026, 10, 16).unwrap(),
+            investor: BrokerInvestor::Foreign,
+            board: BrokerBoard::Regular,
+        };
+        assert_eq!(
+            broker_summary_url("BBCA", &query),
+            "https://www.indopremier.com/module/saham/include/data-brokersummary.php?code=BBCA&start=10/12/2026&end=10/16/2026&fd=F&board=RG"
+        );
+    }
+}