Auto-generate HTML report + modern, research-grade report redesign

[YashvantHange]

What & why

The report (HTML on screen, PDF in print) is Investo's user-facing deliverable, and three things fell short: it was never produced automatically, the look was a deliberately austere print note, and the PDF was not research-grade (uppercase chrome tracked so heavily it rendered/copied as I N V E S T O, plus a fragile running header/footer and tables that could overflow). This PR fixes all three.

Changes

Auto-generate the HTML report

• CLI: investo analyze <name> now writes a self-contained HTML note by default (named investo-<SYMBOL>-<date>.html in the cwd). The notice goes to stderr so --json stays pipeable. --no-html opts out; --html FILE/--pdf still override, and an explicit artifact suppresses the duplicate auto-HTML.
• MCP: analyze_company writes an HTML note too and returns html_report_path (plus generated_at, investo_version, html_bytes); emit_html=false opts out. The tool is now correctly annotated as a file writer.

Modern, visual redesign (render/css.py, render/html.py)

• Design-token system in :root: spacing scale, radii, shadows and a semantic status palette, consumed everywhere (no hardcoded colour at a call site).
• New components: masthead rating block, a row of KPI cards, colour status badges from one shared verdict→colour mapping, card-framed zebra tables, a table of contents, a colophon, <meta name="description">, and accessible table <caption>s.
• Drops the heavy letter-spacing/all-caps that was the root of the I N V E S T O artifact.
• Verdicts use Investo's own vocabulary (rating /100, quality, valuation stance) — never BUY/HOLD/SELL, which would contradict the built-in disclaimer.

Research-grade PDF (print CSS + export.py)

• Per-page running header/footer via a repeating <thead>/<tfoot> group — the reliable technique in Chromium — replacing position:fixed furniture that rendered inverted and clipped body text on full pages.
• Tables/charts fit the page (the 6-column peer table wraps cleanly), table headers repeat across pages, badge/card colours print, and a cover page break.
• Playwright path uses prefer_css_page_size so the document's @page rule owns size/margins.

Verification

• pytest -q — 284 pass (updated the stale "no coloured pill" and read-only-tool tests and the CLI tests; added coverage for auto-HTML on CLI + MCP, badges/cards/TOC, captions, and a no-BUY/SELL guard).
• Rendered RELIANCE.NS end-to-end to HTML and an 11-page PDF via headless Chrome and inspected every representative page (cover, thesis/rating, tables): header/footer correct with no overlap, tables fit, sensible page breaks, colours correct.
• Confirmed the MCP analyze_company path returns a valid html_report_path and that emit_html=false writes nothing.

Note

The stylesheet's original docstring codified "no cards, no coloured pills, status as typography." This PR deliberately reverses that toward a modern, visual look (docstring and the CSS-substring tests updated to match).