0.2.40: bitcoin-denominated line on the LP capital chart

The capital-over-time chart gains a dashed orange series on its own
right-hand ₿ axis: total value (ending balance + distributions) divided
by the BTC price at each statement date — the time-series of the
"In bitcoin terms" box. The history table gains a matching In-bitcoin
column. Frontend-only; prices were already stamped per statement.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/version.ts

@@ -1,4 +1,4 @@
 // Bumped each release so the running build is visible in the UI.
 // If the number shown in the app doesn't match the installed s9pk version,
 // the new frontend isn't actually being served.
-export const APP_VERSION = "0.2.39";
+export const APP_VERSION = "0.2.40";