fix: replace 23 raw setTimeout calls in Logo engine with ManagedTimer to prevent zombie timers

The Logo execution engine (js/logo.js) used 23 raw setTimeout/setInterval calls
for animation dispatch, note scheduling, and completion polling. When users hit
Stop, these timers were never cancelled — creating 'zombie timers' that continue
firing into the next run, causing ghost animations, doubled audio, and UI glitches.

Changes:
- Add js/utils/ManagedTimer.js (277 lines): centralized timer lifecycle manager
  with setTimeout, setGuardedTimeout, setInterval, setGuardedInterval, clearAll,
  and diagnostic getStats/resetStats methods
- Replace all 23 raw setTimeout calls in logo.js with managed/guarded variants
  that auto-cancel when the stop flag is set
- Wire ManagedTimer into RequireJS loader (js/loader.js) as a dependency of Logo
- Call timerManager.clearAll() at the top of doStopTurtles() so every pending
  timer is cancelled the instant the user presses Stop
- Harden Publisher.dataToTags with try/catch + Array.isArray guard for malformed
  project JSON, add module.exports for testability

Tests:
- 55 new tests for ManagedTimer (js/__tests__/ManagedTimer.test.js, 497 lines)
- 4 new tests for Publisher.dataToTags (planet/js/__tests__/Publisher.test.js)
- All 112 test suites pass (3167 tests, 0 failures)

Fixes zombie timer bug in the core execution engine.

Author: Ashutoshx7