feat: Stockbit login for the order book, live quotes and daily history

Opt-in, with the user's own Stockbit session from a pasted
credentialStorage cookie (or IDX_STOCKBIT_REFRESH_TOKEN):

- idx stockbit login/status/logout; session file 0600, tokens never shown
- rotating refresh under a cross-process lock; one refresh+retry on 401
- stocks orderbook: depth with lots and orders, OHLC, value, foreign flow
- --provider stockbit quotes from the session API when logged in
- --history-provider stockbit, and auto under the stockbit provider for
  5d-1y daily windows
- MCP get_orderbook and stockbit_status (17 tools)

Endpoints, units and recorded responses from fzn0x/idx (MIT).

crates/idx-core/src/api/stockbit/parse.rs

@@ -271,7 +271,7 @@ fn wib(local: NaiveDateTime) -> Option<DateTime<FixedOffset>> {
 
 /// A JSON number or numeric string (`"+59.54"`, `"5175.000000"`); `"N/A"`,
 /// `"NA"` and empty strings are absent.
-fn number(value: &Value) -> Option<f64> {
+pub(super) fn number(value: &Value) -> Option<f64> {
     let n = match value {
         Value::Number(n) => n.as_f64()?,
         Value::String(s) => s.trim().parse::<f64>().ok()?,