feat(tui): clear annotations and wrap wide tables

[FireKingY]

Summary

• add C as a document-level clear action in browse mode
• require y/Enter confirmation, with n/Esc cancellation
• refresh folder counts and mark the review as changed after clearing
• reflow wide Markdown tables by cell instead of clipping rendered rows
• when any cell in a table wraps, add full-width separators across every logical table row
• document the new behavior and cover both features with regression tests

Motivation

The existing x action removes annotations from the selected block, but there is no efficient way to reset all annotations for the currently open document.

Wide rendered tables were also clipped at the document viewport. The new layout allocates a narrower width to each column, wraps each cell independently, preserves box-drawing borders, and keeps source offsets on the wrapped content. If any cell in a table wraps, the whole table switches to a full grid so every logical row remains visually separated; tables with no wrapping stay compact.

Effect

The fixture uses CJK and wide characters; the comparison below uses ASCII labels so the
GitHub code block itself does not introduce another display-width variable.

Before — the rendered row exceeds the viewport and the right side is clipped:

┌──────────┬──────────────┬────────────────────
│ location │ model        │ conclusion         ...
├──────────┼──────────────┼────────────────────
│ page 1   │ load switch  │ caller creates ...
│ page 2   │ sender       │ output is cut ...

After — columns are fitted, cells wrap independently, and a wrapped table uses a full grid:

┌──────────────┬──────────────┬───────────────┐
│ location     │ model        │ conclusion    │
│              │              │               │
├──────────────┼──────────────┼───────────────┤
│ page 1       │ load switch  │ caller creates│
│              │              │ Group ...     │
├──────────────┼──────────────┼───────────────┤
│ page 2       │ sender       │ no wrap       │
└──────────────┴──────────────┴───────────────┘

Verification

• cargo fmt --all
• cargo clippy --workspace --all-targets
• cargo test --workspace — 126 tests passed
• cargo build --release -p plannotator-tui

[backnotprop]

Thanks, both pieces work. Two requests before merge:

1. Please move the clear-all key from C to X. Lowercase c and Enter both mean "comment on this block", so a shift slip followed by Enter would wipe every note. X pairs with x, which already removes one block's notes.

2. Please split the table reflow into its own PR. It's a good fix, but it's a rendering change on every wide table and deserves its own review. One note for that PR: the fit gives every column the same width, so short columns get as much room as long ones. Weighting by original width would look a lot better.

Happy to merge the clear-all as soon as it's on X.