feat(chunks): rilevamento universale has_math/has_table + dollarmath plugin

- parser.py: integra dollarmath_plugin (graceful fallback) — blocchi $$…$$ → token math_block atomico
- segmenter.py: gestisce math_block → Block(kind=math, atomic=True, plain_text=[formula])
- packer.py: has_table rileva anche <table> in blocchi html; has_math rileva $$ e \begin{ nel contenuto
- +11 test (parser×3, segmenter×3, packer×5) — totale 65 test

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

tests/chunks/test_packer.py

@@ -116,3 +116,35 @@ def test_assets_empty(cfg):
     blocks = [make_block(1, "Testo.")]
     chunks = pack(blocks, cfg, "test")
     assert chunks[0].assets == []
+
+
+def test_flags_has_math_via_kind(cfg):
+    blocks = [make_block(1, "$$\nE=mc^2\n$$", kind="math", atomic=True)]
+    chunks = pack(blocks, cfg, "test")
+    assert chunks[0].flags["has_math"] is True
+
+
+def test_flags_has_math_via_content_dollars(cfg):
+    # Paragrafo con $$ inline (senza dollarmath plugin attivo)
+    blocks = [make_block(1, "Vedi la formula:\n$$\nx^2\n$$")]
+    chunks = pack(blocks, cfg, "test")
+    assert chunks[0].flags["has_math"] is True
+
+
+def test_flags_has_math_via_content_begin(cfg):
+    blocks = [make_block(1, r"Equazione: \begin{align} x = 1 \end{align}")]
+    chunks = pack(blocks, cfg, "test")
+    assert chunks[0].flags["has_math"] is True
+
+
+def test_flags_has_table_via_html(cfg):
+    html_content = "<table><tr><td>A</td></tr></table>"
+    blocks = [make_block(1, html_content, kind="html", atomic=True)]
+    chunks = pack(blocks, cfg, "test")
+    assert chunks[0].flags["has_table"] is True
+
+
+def test_flags_no_math_plain_text(cfg):
+    blocks = [make_block(1, "Testo normale senza formule.")]
+    chunks = pack(blocks, cfg, "test")
+    assert chunks[0].flags["has_math"] is False