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

docs/ARCHITECTURE.md

@@ -103,6 +103,11 @@ WIB as the fallback.
 - Data is end of day: IDX hides broker codes during trading. Summaries that
   ended before today are cached for 7 days, today's for 5 minutes. Broker
   names come from `broker/codes.tsv` (IDX `GetBrokerCodeList`).
+- Bandarmology (`analysis/bandar.rs`, method `top_concentration_v1`) is pure
+  over one summary: for the top 1/3/5/10 per side, buy value minus sell value
+  in basis points of value traded, with thresholds ±500/±1500 bps taken from
+  fzn0x/idx. A tier with a missing figure has no reading; missing values are
+  never summed as zero. A change to the rules gets a new method name.
 
 ### Capability Gating
 ```