Gossip Stone

## Summary
Shake the swadge to read different things.

## Technical Spec
Use of Accelerometer, and Trophy system.

## UI

Gossip: Shake to get a random message out of several hundred. Progress to getting them all is tracked in a trophy "The Prophecy".
Ask Me Anything: Shake to get one of the classic magic 8-ball responses.
The Prophecy: This menu item appears once you have completed the trophy. The stone has a few more things to say in sequential order. One last hit of dopamine for the most dedicated shakers.

Inputs: Shake to get a message, b to back to the menu, a to get a message (only for the dev environment).

## Mockups

## How to Test

No files or tests are named in the issue. Start by finding existing shake-input menu modes, accelerometer handling, and trophy/achievement code in the firmware, then follow how those modules dispatch A/B inputs. Add matching state flow for Gossip, Ask Me Anything, and The Prophecy using existing patterns, and hook it into navigation/menu registration. Validate by building/flashing the firmware and manually testing that shake advances messages, trophy progress updates, and the Prophecy menu appears only after completion.

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