documents: a press opens its block on the pressed character; a secondary press points

Each drawn text piece keeps its written span, so a press maps back to a
source byte. A secondary press opens nothing: it moves the caret there and
emits DocumentEvent::Pointed with the block's kind, link, picture and
whether it lies in a table or code. Block nodes count from their own start.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/documents/document/tests/mod.rs

@@ -2,7 +2,7 @@ use std::{cell::RefCell, rc::Rc};
 
 use gpui::{Entity, Modifiers, MouseButton, TestAppContext, VisualTestContext, point, px};
 
-use super::{AT_ONCE, DocumentEvent, MarkdownDocument, visual};
+use super::{AT_ONCE, DocumentEvent, MarkdownDocument, edit::Landing, visual};
 use crate::documents::MarkdownMode;
 
 const TEXT: &str = "# Lift\n\nBlend toward white.\n\n- one\n- two\n";
@@ -236,7 +236,7 @@ pub(super) fn type_in(
     cx: &mut VisualTestContext,
 ) {
     document.update_in(cx, |document, window, cx| {
-        document.open(ix, false, window, cx);
+        document.open(ix, Landing::End, window, cx);
         if let (Some(typed), Some(open)) = (typed, &document.open) {
             open.input.update(cx, |input, cx| input.set_text(typed, cx));
         }
@@ -353,11 +353,11 @@ fn a_press_after_a_write_back_waits_for_the_long_read(cx: &mut TestAppContext) {
     let long = format!("A\n\nB\n\nCCCC\n\n{}", "Prose.\n\n".repeat(AT_ONCE / 8 + 1));
     let (document, cx) = open(&long, MarkdownMode::Visual, cx);
     document.update_in(cx, |document, window, cx| {
-        document.open(Some(0), false, window, cx);
+        document.open(Some(0), Landing::End, window, cx);
         let input = document.open.as_ref().expect("open").input.clone();
         input.update(cx, |input, cx| input.set_text("AAAA", cx));
         // B is pressed before the new read lands.
-        document.open(Some(1), false, window, cx);
+        document.open(Some(1), Landing::End, window, cx);
         assert!(document.open.is_none(), "a stale range opens nothing");
     });
     cx.run_until_parked();
@@ -370,6 +370,7 @@ mod history;
 mod links;
 mod look;
 mod place;
+mod point;
 mod toc;
 mod tools;