Add bounded definition and reference navigation for current source drafts

Preserve loaded draft bytes and model history, reject stale workspace and input events, and keep captured Escape under modal priority. Verified 181 focused Windows tests and strict desktop Clippy on exact inputs4; earlier full737 scope and component/native preparation evidence are archived separately. Native navigation acceptance remains pending.

crates/oa-desktop/src/guide.rs

@@ -785,7 +785,7 @@ fn article(topic: Topic) -> Article {
             const {
                 Article {
                     summary: "The text editor and graphical forms edit the same model. Source projects preserve file organization and comments for human review, automation and version control.",
-                    keywords: "text textual source language syntax highlighting lint parser git aliases uuid identity rename diff merge restructuredtext spec canonical parity",
+                    keywords: "text textual source language syntax highlighting lint parser git aliases uuid identity rename diff merge restructuredtext spec canonical parity definition references lexical navigation F12 back",
                     sections: &[
                         walkthrough(
                             "Edit and review source",
@@ -798,6 +798,14 @@ fn article(topic: Topic) -> Article {
                                 "Save all writes the entry and its included UTF-8 files. Review the Git diff before committing, including relationships, traces and diagram changes that belong to the same engineering edit.",
                             ],
                         ),
+                        explain(
+                            "Follow definitions and lexical references",
+                            "Place the caret on a declaration alias or an @reference. Choose Definition (F12) to locate its declaration, or References (Shift+F12) to list lexical uses. Choose a row when a definition is ambiguous, draft or detached. Lexical uses exclude comments and strings; they do not establish typed relationships or resolve an ambiguous alias to one declaration. Back (Alt+Left) returns to the previous source location; if that draft changed, it restores the current cursor instead of an obsolete selection. These shortcuts work while the source editor has focus; the Text toolbar also offers the actions.",
+                        ),
+                        explain(
+                            "Read the navigation scope",
+                            "Queries inspect bounded snapshots of currently loaded drafts, without applying them or loading missing included files. The panel identifies partial scope, draft evidence, detached or unverified files, and alias or ID collisions. Counts show total, displayed and omitted rows. A missing result in partial scope does not establish that the whole project has no match. If sources change, stale rows are disabled; run Definition or References again. Row locations use one-based lines and UTF-8 byte columns. Navigation preserves your source drafts and the accepted model.",
+                        ),
                         explain(
                             "Names, aliases and IDs serve different purposes",
                             "The displayed name is engineering prose. A stable @alias is the readable source reference and need not change when the name changes. UUID identity distinguishes the persistent record. Preserve IDs when revising the same engineering object; changing identity is a deliberate operation that affects references.",