feat(chat): render markdown tables in answers, viewer, and thinking

GFM pipe tables in the shared renderer (TODO.md L6): a table-protection
pass in frontend/assets/markdown.js (fences -> tables -> escape order)
pulls each header+separator+body block out as a placeholder, renders
cells escape-first with the same inline transforms, and reinserts a
semantic <table class="md-table"> inside a horizontal-overflow
.md-table-wrap — so a pipe table in a chat answer, the document
viewer/modal, and the thinking block all render the same semantic
table. Fences win over tables; lone pipes stay text.

- styles.css: .md-table palette rules (PLAN §7.2 tokens, no motion);
  min-width: max-content so a WIDE table keeps its natural width and
  the wrapper is the real scroller (width:100% alone wrapped the wide
  table's cells — proven by the new E2E).
- mock_llm.py: TABLE_TRIGGER ("show me a table") -> byte-stable
  TABLE_ANSWER (3-column table, <img onerror> XSS probe line, wide
  5-column table), checked before DEFLECT_MODE like SUMMARY_MODE.
- tests/fixtures/docs/homelab/tables.md: 3x3 pipe table + pipe-heavy
  fenced block (viewer/fence subject); the shared fixture set grows
  8 -> 9 docs, so every suite pinning the count (added/formats/
  stat-docs/EXPECTED_ROWS) is updated accordingly.
- tests/e2e/test_markdown_tables.py (new, story suite): chat table
  shape + non-deflection, wide-table wrapper scroll (no page
  overflow), XSS probe inert, viewer modal table, fence-not-a-table,
  lone pipe stays text.
- tests/e2e/test_agent_document_tools.py: fix a pre-existing flake —
  the "Calling tool…" label window is ~0.4 s at the mock's 0.1 s
  tool-frame pacing, and a polling expect could stride over it
  (failed 3 of 5 runs on the committed baseline). The pre-submit
  MutationObserver record is the deterministic source of truth; the
  racy to_have_text gate is gone.

uv run pytest: 738 passed, app/ coverage 99% (TOTAL unchanged);
ruff + pyright clean; story E2E 6/6 in isolation; regression E2E
suites (chat_rag, document_viewer, document_summaries, smoke) green.

frontend/assets/styles.css

@@ -576,6 +576,25 @@ html::after {
 .bubble code { font-family: var(--mono); font-size: 0.88em; background: var(--brand-soft); padding: 0.08em 0.35em; border-radius: 5px; }
 .bubble pre code { background: none; padding: 0; }
 
+/* GFM pipe tables (phase 44, 2026-08-27, TODO.md L6): the shared
+   renderer wraps every table in .md-table-wrap — the horizontal
+   scroller, so a wide table scrolls inside the bubble instead of
+   breaking the 46rem column — around a semantic <table class="md-table">
+   (escape-first cells; alignment colons render left, owner decision).
+   Phase-08 tokens only: --line hairline borders and the thead tinted
+   from the plain surface family — --ink on --surface is 14.5:1 (PLAN
+   §7.2), never the brand. The rules are unscoped on purpose: the same
+   renderer serves the chat bubble, the thinking scratchpad, and the
+   document viewer (.doc-md). width:100% stretches narrow tables to the
+   column; min-width:max-content lets a WIDE table keep its natural width
+   so the wrapper is the real scroller (phase 44 task 03: width:100% alone
+   wrapped the wide table's cells and it never overflowed). Static content
+   — no animation (nothing for prefers-reduced-motion to still). */
+.md-table-wrap { overflow-x: auto; }
+.md-table { border-collapse: collapse; width: 100%; min-width: max-content; font-size: 0.9rem; }
+.md-table th, .md-table td { border: 1px solid var(--line); padding: 0.4rem 0.6rem; text-align: left; vertical-align: top; }
+.md-table thead th { background: var(--surface); color: var(--ink); }
+
 .msg.user { justify-content: flex-end; }
 .msg.user .msg-body { align-items: flex-end; }
 .msg.user .bubble {