feat: ATTEDIT — edit block attribute values interactively

- attedit.rs: AtteditCommand picks an INSERT entity then iterates through
  each attribute tag prompting for a new value (Enter keeps existing)
- attedit_pending_handle() / attedit_set_attrs() trait methods inject
  attribute data into the command after entity-pick (avoids document access
  in the command itself)
- cmd_result.rs: NeedPoint handler injects attr data; ReplaceEntity detects
  the __ATTEDIT__ sentinel and calls apply_attedit() on the document
- apply_attedit() encodes tag/value pairs as __ATTEDIT__tag\x01val\x02...
- ROADMAP.md: ATTEDIT marked ✅

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/cmd_result.rs

@@ -8,6 +8,36 @@ impl H7CAD {
         let i = self.active_tab;
         match result {
             CmdResult::NeedPoint => {
+                // If ATTEDIT just completed entity pick, inject attribute data.
+                let attedit_handle = self.tabs[i]
+                    .active_cmd
+                    .as_ref()
+                    .and_then(|c| c.attedit_pending_handle());
+                if let Some(ins_handle) = attedit_handle {
+                    if let Some(acadrust::EntityType::Insert(ins)) =
+                        self.tabs[i].scene.document.get_entity(ins_handle)
+                    {
+                        let attrs: Vec<(String, String)> = ins
+                            .attributes
+                            .iter()
+                            .map(|a| (a.tag.clone(), a.get_value().to_string()))
+                            .collect();
+                        if attrs.is_empty() {
+                            self.command_line
+                                .push_error("ATTEDIT  This INSERT has no attributes.");
+                            self.tabs[i].active_cmd = None;
+                            return Task::none();
+                        }
+                        if let Some(cmd) = &mut self.tabs[i].active_cmd {
+                            cmd.attedit_set_attrs(attrs);
+                        }
+                    } else {
+                        self.command_line
+                            .push_error("ATTEDIT  Please select an INSERT entity with attributes.");
+                        self.tabs[i].active_cmd = None;
+                        return Task::none();
+                    }
+                }
                 let prompt = self.tabs[i].active_cmd.as_ref().map(|c| c.prompt());
                 if let Some(p) = prompt {
                     self.command_line.push_info(&p);
@@ -170,6 +200,27 @@ impl H7CAD {
                 self.refresh_properties();
             }
             CmdResult::ReplaceEntity(handle, new_entities) => {
+                // Detect ATTEDIT sentinel.
+                if new_entities.len() == 1 {
+                    if let acadrust::EntityType::XLine(ref xl) = new_entities[0] {
+                        let layer = xl.common.layer.clone();
+                        if let Some(encoded) = layer.strip_prefix("__ATTEDIT__") {
+                            let label = self.history_label_from_active_cmd(i, "ATTEDIT");
+                            self.push_undo_snapshot(i, label);
+                            crate::modules::home::modify::attedit::apply_attedit(
+                                &mut self.tabs[i].scene.document,
+                                handle,
+                                encoded,
+                            );
+                            self.tabs[i].dirty = true;
+                            self.tabs[i].active_cmd = None;
+                            self.tabs[i].snap_result = None;
+                            self.command_line.push_output("ATTEDIT  Attribute values updated.");
+                            return Task::none();
+                        }
+                    }
+                }
+
                 // Detect SPLINEDIT sentinel: a single XLine with a magic layer name.
                 if new_entities.len() == 1 {
                     if let acadrust::EntityType::XLine(ref xl) = new_entities[0] {