feat: --quick economy preset for short, low-cost tests (CLI + REPL + web)

Billing concern: a full run with 2-3 voters, deep chaining and exhaustive recon
burns a lot of tokens. --quick is one switch for a fast, cheap pass:
one voter, one chain round, light recon (intensity 1), ≤6 agents, eco budget.
Dropping voting from 3 models to 1 is the biggest saver.

- CLI: --quick on run/whitebox/greybox (apply_quick, applied last so it wins)
- REPL: /quick (aliases /economy /eco), listed in help + completion
- web: ⚡ Quick-mode checkbox in the wizard -> /quick in the REPL script
- README: documented in the flags table
- 420 tests passing

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/public/app.js

@@ -532,6 +532,7 @@ async function startExploitation() {
     votes: Number($('#fieldVotes').value) || 3,
     chainDepth: Number($('#fieldChain').value),
     recon: Number($('#fieldRecon').value),
+    quick: $('#fieldQuick') ? $('#fieldQuick').checked : false,
     subscription: state.authMode === 'subscription',
     mcp: $('#fieldMcp').checked,
     agents: [...state.selected],