fix(tui): chapter phase survives trailing-space deletion

[ivanmaierg]

Summary

After picking a book from the palette, the user reported the chapter grid sometimes disappeared and typing a digit afterwards failed to highlight the chapter. Reproducing: pick John → backspace once → type 1 → no chapter menu, no highlight.

Root cause

In src/tui/reader/reader-reducer.ts, the QueryTyped handler required the new query to start with \${displayName} `— note the **trailing space**. Picking a book sets the query to"John ", which matches. But a single backspace produces "John"(no trailing space), which fails the check. The reducer then falls into the book-phase branch, clearsbookChosen, and re-runs book suggestions. Typing "1"next produces"John1"`, which also fails the check (still no space). User is stuck in book phase with no chapter grid.

Fix

The chapter-phase prefix check now accepts the book name with empty rest, leading space, or leading digit. Digit decoding accepts an optional space between the book name and the chapter number, so:

Query	Behavior
John	Stay in chapter phase, no highlight change
John	Stay in chapter phase (unchanged)
John 1	Stay in chapter phase, highlight chapter 1
John1	Stay in chapter phase, highlight chapter 1 (new)
John 10	Stay in chapter phase, highlight chapter 10
John10	Stay in chapter phase, highlight chapter 10 (new)
Joh	Drop to book phase (no longer prefix-match)
Mark	Drop to book phase (different book)

Testing

• 3 new tests in reader-reducer.test.ts cover the trailing-space deletion and bare-digit suffix cases — all fail before the fix and pass after.
• Full suite: 238/240 pass. The remaining 2 failures are pre-existing in src/cli/loading.test.ts and are being fixed in fix(cli): withLoading no-ops when stream is not a TTY #14.
• Manual TUI verification recommended: pick John, backspace, type 1, confirm chapter grid stays visible and highlights chapter 1.