cosmetic: redesign startup header with neoclassical portico and banknote branding

[eggmasonvalue]

Summary

Redesigns the TUI startup header in extensions/startup-header.ts to give SecStack an institutional identity grounded in US capital markets and fundamental securities analysis.

Changes

• Logo & Banknote Lockup:
  • Replaced the wireframe document and circuit lines with a 5-line neoclassical portico (stepped plinth, illuminated columns) and a 3-line banknote note.
  • SECSTACK is centered vertically and horizontally inside the bill, flanked by [$] denomination stamps.
  • Money green borders (theme.fg("success")), gold currency stamps (theme.fg("warning")), and architectural accent columns (theme.fg("accent")).
• Research Pipeline & Dynamic Yielding (Ctrl+O):
  • Overview Mode (Default on launch): Shows the portico, banknote, and the full 5-skill research pipeline: [EDGAR], [SIGNALS], [MARKET], [ANALYSIS], and Norbert Lou's numbers-first Value Investors Club writing ([VIC PITCH]).
  • Inspection Mode (Ctrl+O): When tools are expanded to inspect raw filings or command output, the header automatically collapses to the compact 5-line portico and banknote, yielding screen real estate to the tool outputs.
• Bootstrap Settings:
  • Updated scripts/bootstrap.mjs to selectively set quietStartup: true in ~/.pi/secstack-agent/settings.json so Pi's raw resource dump is silenced.
• Responsive Layout:
  • Wide (>= 42 cols): Full portico and 26-column banknote note.
  • Compact (34..41 cols): Slimmer 33-column banknote lockup.
  • Narrow (< 34 cols): Minimal bracketed wordmark.