[TMCU-809] [Pure Black] predict: feed and chart masks break under pure-black dark mode

@georgewrmarshall is already working on this.

Since Jul 3, 2026.

### Description\n\nMirrors Jira [TMCU-809](https://consensyssoftware.atlassian.net/browse/TMCU-809).\n\nPart of epic #1271 / [TMCU-622](https://consensyssoftware.atlassian.net/browse/TMCU-622).\n\n**Jira status:** To Do\n\n### Jira details\n\n## Getting Started\n\nTo reproduce the pure-black UI issues in scope for this ticket, you need to enable the preview flag locally. It is **off by default**.\n\n**1. Enable the flag**\n\nIn your local (copy from if you don't have one), set:\n\n\n\n**2. Rebuild the JS bundle**\n\nThe flag is inlined at bundle time by \u2014 a Metro hot reload is **not** enough. Restart with a clean cache:\n\n\n\nIf you changed native code recently, also re-run Usage Error: Couldn't find a script named "start:ios".

$ yarn run [--inspect] [--inspect-brk] [-T,--top-level] [-B,--binaries-only] [--require #0] ... / Usage Error: Couldn't find a script named "start:android".

$ yarn run [--inspect] [--inspect-brk] [-T,--top-level] [-B,--binaries-only] [--require #0] ....\n\n**3. Switch the app to Dark mode**\n\nPure black only takes effect in dark mode (light mode is intentionally unchanged). Settings \u2192 General \u2192 Theme \u2192 **Dark**.\n\n**4. How it works (FYI)**\n\n* is the first import in and mutates _before_ the twrnc preset bakes them into Tailwind config. This is the only reason / / etc. resolve to pure-black values.\n* Two stopgap helpers in \u2014 (returns ) and \u2014 are how existing surfaces have been elevated to avoid collapse. Prefer these over hardcoding tokens; they no-op when the flag is off, so they're safe to land before the global rollout.\n\n**5. Turning it off**\n\nSet (or remove the line) and Usage Error: Couldn't find a script named "watch:clean".

$ yarn run [--inspect] [--inspect-brk] [-T,--top-level] [-B,--binaries-only] [--require #0] ...\n