Fix banner contrast across terminals

[tomcasaburi]

GitHub issue:

• Title: Fix banner contrast across terminals
• Description: The daemon banner uses hardcoded light foreground colors when stdout is a TTY, so the Bitsocial wordmark becomes unreadable on light terminal themes. In non-TTY/container logs, color is disabled entirely and the banner loses the visual hierarchy expected from src/cli/ascii-banner.ts.

Plan:

• Make banner rendering testable without writing directly to process stdout.
• Use readable foreground defaults for both dark and light terminal themes.
• Preserve a clean no-color fallback for plain logs and terminals that opt out of ANSI color.
• Add focused tests for color, no-color, and light-background environment behavior.

[tomcasaburi]

Progress update:

• Implemented a renderable banner helper so color behavior can be tested directly.
• Removed the fixed near-white wordmark color and now leave the wordmark/ring on the terminal default foreground.
• Switched the blue accent to broadly supported ANSI bright blue.
• Added tests for no-color, TTY color, non-TTY plain, forced color, and FORCE_COLOR=0 behavior.
• TypeScript build and test build are passing locally; full CLI test suite is next.

[tomcasaburi]

Verification update:

• npm run build && npm run build:test passed with Node v22.13.0 after nvm use.
• First full npm run test:cli run hit a daemon/Kubo shutdown timing failure in test/cli/daemon.test.ts, unrelated to the banner change.
• The exact failing shutdown test passed on a focused rerun.
• A second full npm run test:cli run passed: 29 test files, 214 passed, 1 skipped.

[tomcasaburi]

Final implementation update:

• Banner wordmark/ring now use the terminal default foreground instead of a fixed near-white color, so light and dark terminal themes stay readable.
• Banner blue accent now uses ANSI bright blue instead of 24-bit truecolor for broader terminal compatibility.
• bitsocial daemon forces the banner accent color for startup/log output, including non-TTY Docker/systemd-style logs, while NO_COLOR still disables it.
• Added direct banner renderer tests for no-color, TTY color, forced log color, FORCE_COLOR, and FORCE_COLOR=0.
• During full verification I found and fixed a separate daemon shutdown race tracked in Register daemon shutdown cleanup before readiness #59.
• Verified with npm run build && npm run build:test, focused shutdown test, and full npm run test:cli pass: 29 files, 215 passed, 1 skipped.