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.

docs/language.html

@@ -2633,6 +2633,23 @@ trace links, occurrence identity, comments and file ownership. Each open file
 retains its own unapplied draft across file navigation. Located lint diagnostics
 refer to the raw draft bytes rather than an identity-stabilized intermediate.
 Property editing MUST NOT silently discard a pending source draft.</p>
+<p>In Textual model, place the caret on a declaration alias or an <span class="docutils literal">&#64;reference</span>
+and choose <strong>Definition</strong> (<span class="docutils literal">F12</span>) or <strong>References</strong> (<span class="docutils literal">Shift+F12</span>).
+<strong>Back</strong> (<span class="docutils literal">Alt+Left</span>) returns to the previous source location in this
+workspace. These shortcuts act while the source editor has focus; the Text
+toolbar also exposes the actions. If the previous draft changed, Back restores
+its current cursor rather than reusing an obsolete selection.</p>
+<p>Symbol navigation reads bounded snapshots of the currently loaded source
+drafts. It does not apply drafts or load missing included files. The results
+identify partial scope, draft evidence, detached or unverified files, alias
+ambiguity and authored-ID collisions. Draft, detached and ambiguous definition
+candidates require an explicit row choice. References are lexical uses of an
+alias, not a list of resolved typed relationships; comments and strings are
+excluded. Declaration and use counts include any rows omitted by the result
+limits. If sources change, stale rows cannot navigate: run the query again.
+Navigation MUST preserve the accepted model and every source draft, and select
+locations in the original UTF-8 bytes. Displayed locations use one-based lines
+and UTF-8 byte columns.</p>
 <p>Changing a graphical UUID must atomically update map keys and every reference.
 Alias changes preserve UUID identity. Deletion must account for owned elements,
 incident relationships, ordered occurrences, and diagram placements without