fix: v0.9.3 plan usage instead of API-price cost; larger footer

- Footer shows "5h N%" when Claude sends rate_limits (Pro/Max); the
  dollar figure is an API-price estimate, so it is kept only for API-key
  billing. Sessions tooltip follows suit. Closes #40
- Bottom row: 40px, larger hints, bold 1rem usage meters with wider bars;
  narrow windows drop hints instead of clipping the meters. Closes #41
- bats setup unsets inherited DevDesk env so tests pass inside DevDesk

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WHRLCCdXYm41Qx5kNhehaP

web/src/sessions.js

@@ -278,7 +278,8 @@ export class SessionsPanel {
     const title = [
       s.dir,
       status.key === 'waiting' && s.status?.message,
-      s.context?.model && `${s.context.model}${s.context.cost_usd != null ? ` · $${s.context.cost_usd.toFixed(2)}` : ''}`,
+      // rate_limits means a Pro/Max plan, where cost_usd is only an API-price estimate
+      s.context?.model && `${s.context.model}${s.context.rate_limits ? '' : s.context.cost_usd != null ? ` · $${s.context.cost_usd.toFixed(2)}` : ''}`,
     ].filter(Boolean).join('\n');
     const iconButton = (label, glyph, onclick, extra = '') =>
       el('button', { class: `dd-icon-btn ${extra}`, type: 'button', title: label, 'aria-label': `${label} ${s.name}`, onclick }, glyph);