Initial commit: Chatter — assistive-writing app for reMarkable Paper Pro Move

Direct-framebuffer ink pipeline (stock-quality strokes), finger-wipe erase,
growable scrolling canvas with color-ghost cleanup, bidirectional toggle with a
persistent 4-finger return launcher, instant button feedback. Includes prebuilt
aarch64 binaries (dist/), build/deploy/install scripts, a user guide, and a
complete technical reference.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

doc/Chatter_application_proposal.md

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+# Chatter — A custom application for the reMarkable tablet
+
+## Background
+
+I am helping someone who has a hard time speaking and who is using a 
+[reMarkable tablet](https://image.email.remarkable.com/lib/fe3511737364047c771479/m/1/e39f7595-fc99-4f8c-b7e3-dde042451668.pdf)
+in conversations to write what she cannot say.  I believe that the
+reMarkable table is the best choice for a digital handwriting interface.
+However, the tablet is designed for taking notes that can be preserved or even
+transformed into digital text. It is not intentionally designed to be used as an
+*assistive-speech device*. There are also a wide variety of customizable options
+that are typically unnecessary if using the table in that way.
+
+## Project goal
+
+I would like to create a replacement for the reMarkable graphical user interface
+(GUI) that would be tailored for using the table as an assistive-speech device.
+This interface would not replace the standard GUI; choosing tablet settings for
+the writing style or other interface parameters would still be done in the
+standard GUI.  This assumes, however, that the user can change settings as needed
+in the normal way (or that technical help is available when necessary).
+The goal here is to make the interaction with the tablet during conversation as
+simple as possible.
+
+The custom application's name is "Chatter", with the implication that
+conversational interaction can be accelerated.  The word also can refer to the
+speaker as well as to the result of speaking.
+
+## User-interface elements
+
+In watching the user with the tablet's standard GUI, I have noticed a confusion
+about whether writing or erasing is the active mode. A simple action like
+clearing the page requires several user-interface gestures.  The user's
+inability to easily use the table is often not wholly due to a lack of technical
+understanding but a failure to remember technical details when they are not
+intuitive.
+
+Chatter implements four actions, ordered here by their potential frequency of
+use:
+
+- *Erase part of the text* — This should be simple and intuitive gesture.  For
+  example, I have seen the user wiping her fingers back and forth across some
+  text to erase it.
+
+- *Erase the page* — Erasing the entire page should be a single gesture. The
+  blank page that results continues to use the current pen styling and other
+  parameters set in the standard GUI.
+
+- *Save current text to a file named by time* — The current page is saved
+  with an automatically generated name that contains a human-readable text of the year,
+  month, date, hour, minutes and seconds.  The seconds may not be necessary, but
+  I would rather have an elaborate name than risk losing a previously saved
+  file.  These Chatter transcripts should be saved to a separate directory to
+  avoid cluttering the main screen. Deleting and renaming these files are
+  possible through the standard GUI; a tutorial about that should be provided if
+  the user expresses interesting in managing the transcripts in that way.
+
+- *Toggle between the standard GUI and Chatter* — The standard GUI should still
+  be available through a single gesture; Chatter augments the tablet's interface
+  and does not replace it.  However, returning to Chatter will require an
+  addition to the standard GUI that will be memorable for the user.
+
+### Implementation considerations
+
+If the table can differentiate between a fingertip and the stylus, then erasing
+part of the text as well as the entire page could be implemented by a finger
+gesture. Rubbing the finger back and forth of an area of text could remove any
+drawing close to that area (where "close" might be determined experimentally
+working with the user).  A diagonal stroke with a finger from upper-right to
+lower-left would be interpreted as a request to erase the entire page.
+
+If differentiating between fingertip and stylus is not possible, then Chatter
+should define some shortcut for the stylus that easily creates the standard
+region-based erase gesture.  For example, if the user circles an area twice,
+that could signify erasure, not drawing.  A stylus stroke from upper-right to
+lower-left could specify whole-page erasure, even if the finger stroke
+method is also possible.
+
+The toggling the standard GUI and saving a file are not actions that the user
+would frequently perform.  I think that small icons at the bottom of the page,
+activated by stylus or finger, would provide an ongoing reminder of how to do
+those actions.  The standard GUI will need to provide some way of switching to
+Chatter; the user should suggest a method that she would find memorable.
+
+
+## Deployment and refinement
+
+A developer working on this project will install the custom GUI on the user's
+tablet.  After verifying that the installation is successful, the developer will
+watch the user with the tablet to evaluate the current interface efficiency of
+Chatter, talking with the user about what is missing and what could be improved.
+Paying attention to the user's questions that begin, "Why does this..." and "Why
+doesn't this..." will be very important in refining the design. I believe that
+using a custom interface for the tablet might also inspire the user to suggest
+other features that would not be obvious to the developers.
+