Add a sheet qualifier: "Blatt!Tabelle::Zelle", table names unique per sheet

Table names were document-unique; now they're unique per sheet only --
two different sheets may each hold a table called "Umsatz". A plain,
unqualified reference (Umsatz!B2 / Umsatz::B2, unchanged from before)
resolves to the table on the SAME sheet as the formula referencing it
when the name is otherwise ambiguous, falling back to the single
document-wide match when it isn't ambiguous at all -- exactly as
before for every existing formula. The new explicit 3-part form
(Analyse!Umsatz::B2, quoted where a name has spaces) always targets
the named sheet's table regardless of where the formula itself lives,
for the case that's still genuinely ambiguous.

Engine: parser.ts's afterFirstQualifierToken() disambiguates via
lookahead -- "X!Y::" (a name, then "::") is the new 3-part sheet+table
form; a bare "X!Y" keeps its original single-qualifier meaning, so
every formula written before this exists still parses identically.
CellNode/RangeNode gain an optional sheetQualifier field.
Workbook.resolveTableName(name, sheetName?) implements the resolution
policy; TableModel gains sheetName. precedentsOf() now also sets
homeTableId (previously only evaluateCell did), so graph edges use the
same same-sheet-preference resolution an evaluation would.

Store: table name uniqueness checks (addTable, renameObject) are now
scoped to the target sheet instead of the whole document. Point-mode's
qualifyRef() inserts the full "Blatt!Tabelle::" form only when the
clicked table's name is genuinely ambiguous and lives on a different
sheet than the editor; otherwise the simple form, unchanged.

200 tests passing (19 new), vue-tsc and eslint clean, verified live in
the running app: renamed a Blatt-2 table to the same name as Analyse's
seed "Umsatz", confirmed an unqualified reference resolves per-sheet,
an explicit sheet-qualified one always targets the named sheet, and
the original sheet's own formulas are unaffected.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/store/__tests__/document.spec.ts

@@ -1047,6 +1047,88 @@ describe('formula "point mode" (click/drag a cell to insert a reference)', () =>
     s.registerFormulaEditor(null);
     expect(s.formulaPointModeActive()).toBe(false);
   });
+
+  it('a click on a same-named table on a DIFFERENT sheet inserts the full "Blatt!Tabelle::" form', () => {
+    const s = fresh();
+    const home = s.addTable(s.doc.activeSheetId); // lives on "Analyse"
+    const blatt2 = s.doc.sheets[1].id; // "Blatt 2"
+    const other = s.addTable(blatt2);
+    s.renameObject(other, 'Umsatz'); // now ambiguous: Analyse already has an "Umsatz" too
+    const ed = mockEditor(home, '=');
+    s.registerFormulaEditor(ed.handle);
+    s.pointClick(other, 0, 0);
+    expect(ed.text).toBe("='Blatt 2'!Umsatz::A1"); // plain "Umsatz!A1" would be ambiguous
+  });
+});
+
+describe('cross-sheet formulas: sheet qualifier + per-sheet table name uniqueness', () => {
+  it('renaming a table to a name already used on a DIFFERENT sheet is now allowed', () => {
+    const s = fresh();
+    const blatt2 = s.doc.sheets[1].id;
+    const id = s.addTable(blatt2);
+    s.renameObject(id, 'Umsatz'); // "Umsatz" already exists, but on the OTHER (Analyse) sheet
+    expect(s.tableById(id)!.name).toBe('Umsatz');
+  });
+
+  it('renaming a table to a name already used on the SAME sheet still gets uniquified', () => {
+    const s = fresh();
+    const id = s.addTable(s.doc.activeSheetId); // Analyse already has an "Umsatz"
+    s.renameObject(id, 'Umsatz');
+    expect(s.tableById(id)!.name).toBe('Umsatz 2');
+  });
+
+  it("inserting a new table defaults its name against only its OWN sheet's objects", () => {
+    const s = fresh();
+    const blatt2 = s.doc.sheets[1].id;
+    // Blatt 2 starts empty -- its first new table can be plain "Tabelle",
+    // unaffected by Analyse already having several named objects.
+    const id = s.addTable(blatt2);
+    expect(s.tableById(id)!.name).toBe('Tabelle');
+  });
+
+  it('an unqualified, cross-sheet-ambiguous table name resolves to the one on the SAME sheet as the formula', () => {
+    const s = fresh();
+    const analyse = s.doc.activeSheetId; // capture before addTable()'s activeSheetId side effect
+    const blatt2 = s.doc.sheets[1].id;
+    const dupId = s.addTable(blatt2);
+    s.renameObject(dupId, 'Umsatz'); // now two tables named "Umsatz", one per sheet
+    s.setCellInput(dupId, 1, 1, '777'); // Blatt 2's own Umsatz!B2
+
+    const blatt2RefId = s.addTable(blatt2);
+    s.setCellInput(blatt2RefId, 0, 0, '=Umsatz!B2');
+    expect(s.cellValue(blatt2RefId, 0, 0)).toBe(777); // resolves to Blatt 2's own Umsatz
+
+    const analyseRefId = s.addTable(analyse);
+    s.setCellInput(analyseRefId, 0, 0, '=Umsatz!B2');
+    expect(s.cellValue(analyseRefId, 0, 0)).toBe(1200); // resolves to Analyse's (seed) Umsatz
+  });
+
+  it('an explicit "Blatt!Tabelle::Zelle" reference always targets that sheet\'s table', () => {
+    const s = fresh();
+    const analyse = s.doc.activeSheetId; // capture before addTable()'s activeSheetId side effect
+    const blatt2 = s.doc.sheets[1].id;
+    const dupId = s.addTable(blatt2);
+    s.renameObject(dupId, 'Umsatz');
+    s.setCellInput(dupId, 1, 1, '777'); // Blatt 2's Umsatz!B2
+
+    const refId = s.addTable(analyse); // lives on Analyse
+    s.setCellInput(refId, 0, 0, "='Blatt 2'!Umsatz::B2"); // explicit -> Blatt 2's, not Analyse's own
+    expect(s.cellValue(refId, 0, 0)).toBe(777);
+    s.setCellInput(refId, 0, 1, '=Analyse!Umsatz::B2'); // explicit -> Analyse's own
+    expect(s.cellValue(refId, 0, 1)).toBe(1200);
+  });
+
+  it('deleting the sheet that owned one of two same-named tables leaves the other resolvable unqualified', () => {
+    const s = fresh();
+    const analyse = s.doc.activeSheetId; // capture before addTable()'s activeSheetId side effect
+    const blatt2 = s.doc.sheets[1].id;
+    const dupId = s.addTable(blatt2);
+    s.renameObject(dupId, 'Umsatz');
+    s.deleteSheet(blatt2); // the ambiguity is gone -- only Analyse's Umsatz remains
+    const refId = s.addTable(analyse);
+    s.setCellInput(refId, 0, 0, '=Umsatz!B2');
+    expect(s.cellValue(refId, 0, 0)).toBe(1200);
+  });
 });
 
 describe('text box objects', () => {