feat(webapp): completing spans server-side no longer write-after-read, improving efficiency and perf #3530

Job	Run time
e2e / 🧪 CLI v3 tests (ubuntu-latest - pnpm)	2m 37s
typecheck / typecheck	2m 54s
e2e / 🧪 CLI v3 tests (windows-latest - pnpm)	2m 51s
e2e / 🧪 CLI v3 tests (ubuntu-latest - npm)	2m 23s
e2e / 🧪 CLI v3 tests (windows-latest - npm)	2m 41s
units / packages / 🧪 Unit Tests: Packages (1, 1)	2m 54s
units / webapp / 🧪 Unit Tests: Webapp (8, 8)	2m 55s
units / webapp / 🧪 Unit Tests: Webapp (2, 8)	2m 53s
units / webapp / 🧪 Unit Tests: Webapp (5, 8)	2m 53s
units / webapp / 🧪 Unit Tests: Webapp (3, 8)	2m 36s
units / webapp / 🧪 Unit Tests: Webapp (1, 8)	2m 55s
units / webapp / 🧪 Unit Tests: Webapp (7, 8)	2m 12s
units / internal / 🧪 Unit Tests: Internal (3, 8)	2m 54s
units / internal / 🧪 Unit Tests: Internal (2, 8)	2m 53s
units / internal / 🧪 Unit Tests: Internal (1, 8)	2m 53s
units / internal / 🧪 Unit Tests: Internal (4, 8)	2m 52s
units / internal / 🧪 Unit Tests: Internal (5, 8)	2m 54s
units / webapp / 🧪 Unit Tests: Webapp (6, 8)	2m 56s
units / webapp / 🧪 Unit Tests: Webapp (4, 8)	2m 52s
units / internal / 🧪 Unit Tests: Internal (8, 8)	1m 46s
units / internal / 🧪 Unit Tests: Internal (7, 8)	2m 53s
units / internal / 🧪 Unit Tests: Internal (6, 8)	2m 52s
units / packages / 📊 Merge Reports	1s
units / webapp / 📊 Merge Reports	1s
units / internal / 📊 Merge Reports	1s
	1h 0m 32s

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