fix: report line-only coverage honestly and tighten Bun test helpers

The generated HTML and Cobertura reports no longer show unmeasured
branch and function coverage as 100%. Poll and waitFor deadlines use
performance.now so frozen dates cannot make them loop forever, the
malformed-configuration test covers undefined again next to the empty
array, compose health checks honor PORT, and the migration spec lists
only what is still open.

Refs #291, #292, #293

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/services/planning-objectives.spec.ts

@@ -174,6 +174,7 @@ describe('composable planning objectives', () => {
 
 	it.each([
 		null,
+		[undefined],
 		[[]],
 		{ ...OPTIMIZATION_PRESETS.shortSequenceDeficit, conditions: ['internal', 'internal'] },
 		{ ...OPTIMIZATION_PRESETS.longestWorkSequence, direction: 'up' },