feat(text): in-place editors for all text entities

Route every text-bearing entity to an in-place editor instead of the
command line: a plain text box for single-line text (Text, attributes,
dimension override, tolerance) and the rich MText editor for MText /
MultiLeader. A Leader resolves to the entity it annotates.

- TEXT places a plain text box at the click; double-click edits in place.
- DDEDIT and double-click on any text entity open the matching editor.
- MLEADER places the leader then opens the MText editor on its content.
- LEADER follows the classic flow: points, Enter, then a linked empty
  MText annotation opens in the editor; the leader's annotation_handle
  links the pair so they edit/erase as a unit.

Adds shared field read/write helpers and a begin_text_edit router, plus
CommitAndEditText / CommitManyAndEditText results that commit an entity
and open its editor (commit_entity now returns the new handle).

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/command/mod.rs

@@ -51,6 +51,16 @@ pub enum CmdResult {
     CommitEntity(EntityType),
     /// Commit an acadrust entity to the document and end the command.
     CommitAndExit(EntityType),
+    /// Commit an acadrust entity, end the command, and open the in-place text
+    /// editor on it (used by MLEADER to type the annotation after placement).
+    CommitAndEditText(EntityType),
+    /// Commit several entities, end the command, and open the in-place text
+    /// editor on the one at `edit_index` (used by LEADER to place the leader
+    /// line plus an empty MText annotation, then type into the MText).
+    CommitManyAndEditText {
+        entities: Vec<EntityType>,
+        edit_index: usize,
+    },
     /// Create a block definition from existing entities and insert one reference.
     CreateBlock {
         handles: Vec<Handle>,
@@ -126,6 +136,9 @@ pub enum CmdResult {
     SetPlotWindow { p1: Vec3, p2: Vec3 },
     /// Replace the text content of a Text/MText entity in-place.
     DdeditEntity { handle: Handle, new_text: String },
+    /// Open the in-place editor (plain box or rich MText editor, per type) for
+    /// a text-bearing entity picked by a command such as DDEDIT.
+    EditTextEntity { handle: Handle },
     /// Open the in-place MText editor (formatting toolbar + multi-line text
     /// area with live viewport preview). `handle` is `Some` when editing an
     /// existing MText, `None` when creating a new one at `pos`.
@@ -135,6 +148,15 @@ pub enum CmdResult {
         initial: String,
         height: f64,
     },
+    /// Open the in-place single-line TEXT editor (a plain text-entry box, no
+    /// formatting toolbar). `handle` is `Some` when editing an existing Text,
+    /// `None` when creating a new one at `pos`.
+    OpenTextEditor {
+        pos: Vec3,
+        handle: Option<Handle>,
+        initial: String,
+        height: f64,
+    },
     /// Apply new pattern/scale/angle to an existing hatch entity.
     HatcheditApply {
         handle: Handle,