fix: finalize reviewed drawing and interaction paths

Reset stale geometry when automation replaces a drawing and resolve material paths from its directory. Cover precise indexed snapping, large-coordinate line intersections, leader ordering, invalid image buffers and browser clipboard fallback. Preserve Options dialog resizing.

Validation: cargo test --workspace --all-features (866 passed); wasm32 application check; Node clipboard regression check; Python binding tests (3 passed).

scripts/test_web_clipboard.cjs

@@ -0,0 +1,42 @@
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+(async () => {
+    const source = fs.readFileSync(path.join(__dirname, '../web/clipboard.js'), 'utf8');
+    const { copyHistory } = await import(`data:text/javascript;base64,${Buffer.from(source).toString('base64')}`);
+    const text = 'LINE\n0,0\n10,10\n<unchanged & literal>\n';
+    let copied;
+    Object.defineProperty(globalThis, 'navigator', { configurable: true, value: {
+        clipboard: { writeText: async value => { copied = value; } },
+    }});
+    assert.equal(await copyHistory(text, 'Copy manually', 'Close'), true);
+    assert.equal(copied, text);
+    const dialogs = [];
+    globalThis.document = {
+        body: { append: dialog => dialogs.push(dialog) },
+        createElement: tag => ({
+            tag, style: {}, events: {},
+            setAttribute(key, value) { this[key] = value; },
+            append(...children) { this.children = children; },
+            addEventListener(event, handler) { this.events[event] = handler; },
+            showModal() { this.open = true; },
+            focus() { this.focused = true; },
+            select() { this.selected = true; },
+            close() { this.events.close(); },
+            remove() { this.removed = true; },
+        }),
+    };
+    for (const clipboard of [{ writeText: async () => { throw Error('Denied'); } }, undefined]) {
+        navigator.clipboard = clipboard;
+        assert.equal(await copyHistory(text, 'Copy manually', 'Close'), false);
+        const dialog = dialogs.at(-1);
+        const [label, field, close] = dialog.children;
+        assert.equal(label.textContent, 'Copy manually');
+        assert.equal(field.value, text);
+        assert.ok(field.readOnly && field.focused && field.selected && dialog.open);
+        close.onclick();
+        assert.ok(dialog.removed);
+    }
+    console.log('Browser clipboard: success, denied and unavailable paths passed.');
+})().catch(error => { console.error(error); process.exitCode = 1; });