Render research prose as Markdown with RTL tables

The analysis-and-research.md content has markdown tables (ציר דיוני)
and inline formatting like **label:** strong runs, which were
rendering as raw pipes and dashes because the compose page used
whitespace-pre-line on plain text.

Add a reusable <Markdown> component backed by react-markdown +
remark-gfm with a custom `components` map that styles paragraphs,
lists, blockquotes, strong runs, and especially GFM tables for RTL
+ aligned columns:

- table: table-auto + border-collapse, wrapped in overflow-x-auto
  so very wide tables don't push the parent card out
- th: whitespace-nowrap so the header row sets column widths and
  every row border lines up row-to-row
- everything text-right + the whole block gets dir="rtl" at the root

Use it in three places on the compose screen:
- ProseSection (represented_party, procedural_background,
  agreed_facts, disputed_facts)
- Conclusions card
- SubsectionCard field content — threshold_claims and issues have
  the same markdown shape in their fields[]

react-markdown + remark-gfm added (~30KB gzipped).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web-ui/package.json

@@ -23,6 +23,8 @@
     "react-dom": "19.2.4",
     "react-dropzone": "^15.0.0",
     "react-hook-form": "^7.72.1",
+    "react-markdown": "^10.1.0",
+    "remark-gfm": "^4.0.1",
     "shadcn": "^4.2.0",
     "sonner": "^2.0.7",
     "tailwind-merge": "^3.5.0",