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

web/src/content/docs/cli/stocks.md

@@ -47,6 +47,32 @@ codes during trading. Buyers and sellers are ranked separately on gross
 lots, so a broker can appear on both sides. The source rounds figures of a
 million and more to one decimal, and the output says so.
 
+## Bandarmology
+
+```bash
+idx stocks bandar BBCA
+idx stocks bandar BBCA --from 2026-10-12 --to 2026-10-16 --top 3
+idx stocks screen --filter high-volume | jq -r '.[].symbol' | idx stocks bandar -
+```
+
+`bandar` reads the broker summary: for the top 1, 3, 5 and 10 brokers on each
+side, the buyers' value minus the sellers' value as a share of the value
+traded. The headline tier (`--top`, default 5) gives the signal:
+
+| Top-N buy minus sell, % of value | Signal |
+| --- | --- |
+| +15% or more | big accumulation |
+| +5% to +15% | accumulation |
+| within ±5% | neutral |
+| -15% to -5% | distribution |
+| -15% or less | big distribution |
+
+Several symbols give a screen ranked by that figure (at most 100, one request
+each), and it takes the same date and filter flags as `broker`. It is a
+heuristic: a broker trades for many clients, and a broker on both sides of
+the summary is listed, since its gross figures overstate which way it traded.
+The JSON names the rules in `method` (`top_concentration_v1`).
+
 ## Analysis
 
 | Command | What it computes |