feat: bandarmology (idx stocks bandar, analyze_bandar)

`idx stocks bandar SYMBOL...` reads the broker summary: for the top 1, 3,
5 and 10 brokers per side, buy value minus sell value in basis points of
value traded, with a signal from big accumulation to big distribution on
the headline tier (--top, default 5). Several symbols give a screen ranked
by that figure (at most 100, one request each), which pipes from
`stocks screen`. The MCP server exposes it as analyze_bandar (20 symbols).

- analysis/bandar.rs is pure and versioned (`top_concentration_v1`):
  integer basis points, no figure missing counted as zero, buy/sell VWAP
  from exact averages, and the brokers on both sides listed because their
  gross figures overstate their direction.
- Thresholds (±5%/±15%) follow fzn0x/idx (MIT); docs call them heuristics.
- Invalid input fails a screen at once; other errors fail one symbol and
  are warned about on stderr.

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

crates/idx-mcp/src/params.rs

@@ -115,10 +115,9 @@ pub struct AnalyzeParams {
     pub kinds: Option<Vec<AnalysisKind>>,
 }
 
+/// Which sessions and trades a broker tool covers.
 #[derive(Debug, Deserialize, JsonSchema)]
-pub struct BrokerParams {
-    /// IDX ticker, e.g. "BBCA".
-    pub symbol: String,
+pub struct BrokerScope {
     /// One session, YYYY-MM-DD. Omit date, from and to for the latest session with trades.
     #[serde(default)]
     pub date: Option<String>,
@@ -139,6 +138,25 @@ pub struct BrokerParams {
     pub board: Option<String>,
 }
 
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct BrokerParams {
+    /// IDX ticker, e.g. "BBCA".
+    pub symbol: String,
+    #[serde(flatten)]
+    pub scope: BrokerScope,
+}
+
+#[derive(Debug, Deserialize, JsonSchema)]
+pub struct BandarParams {
+    /// IDX tickers, e.g. ["BBCA", "BBRI"]; the `.JK` suffix is optional. At most 20.
+    pub symbols: Vec<String>,
+    #[serde(flatten)]
+    pub scope: BrokerScope,
+    /// Tier behind the headline signal: 1, 3, 5 or 10 brokers per side (default 5).
+    #[serde(default)]
+    pub top: Option<u8>,
+}
+
 #[derive(Debug, Deserialize, JsonSchema)]
 pub struct ShareholdersParams {
     /// IDX ticker, e.g. "BBCA".