QVAC-20608 test[skiplog]: stabilize sdk e2e bootstrap downloads

[Victor-Rodzko]

🎯 What problem does this PR solve?

• SDK e2e bootstrap could start too many registry model downloads at once, making transient REQUEST_TIMEOUT failures more likely on slower runners and mobile networks.
• Desktop CI cache config could shadow the e2e registry retry/timeout fixture, so bootstrap was not guaranteed to use the intended registry stability settings.

📝 How does it solve it?

• Adds a bounded bootstrap download queue with explicit desktop/mobile defaults and a second retry pass for first-pass download failures.
• Keeps desktop CI-owned cacheDirectory merged with e2e-owned registry retry/timeout defaults before SDK initialization.
• Makes desktop/mobile download targets explicit and ignores the generated merged desktop config file.

🧪 How was it tested?

• npm run build in packages/sdk/e2e
• Local macOS smoke: reports/local-local-1781203047990 (100/100 passed)
• Local iOS smoke: reports/local-local-1781203876456 (84 passed, 16 expected skipped, 0 failed)
• GitHub Actions run 27399817010: desktop macOS/Linux/Windows bootstrap applied the generated config and pre-cached 39 constants with concurrency=6; mobile Android/iOS applied the mobile config and pre-cached 25 constants with concurrency=4. No bootstrap REQUEST_TIMEOUT, HypercoreError, or final download failures were found.
• GitHub Actions run 27403773340: Linux/Windows desktop and Android/iOS mobile bootstrap completed with the same bounded concurrency. Android had one registry REQUEST_TIMEOUT that recovered on internal retry attempt 1/5; Windows/iOS failures were later test failures, and the macOS desktop job was cancelled before bootstrap logs were available.

[github-actions]

QVAC E2E — android — ✅ all tests passed (86/100, 2380s)

Config: suite=smoke · filter=(none) · exclude=(none)
View run · Artifacts: reports · Device Farm logs

[github-actions]

QVAC E2E — ios — ✅ all tests passed (84/100, 1142s)

Config: suite=smoke · filter=(none) · exclude=(none)
View run · Artifacts: reports · Device Farm logs

[github-actions]

QVAC E2E — windows — ✅ all tests passed (100/100, 691s)

Config: suite=smoke · filter=(none) · exclude=(none)
View run · Artifacts: reports

[github-actions]

QVAC E2E — linux — ✅ all tests passed (100/100, 489s)

Config: suite=smoke · filter=(none) · exclude=(none)
View run · Artifacts: reports

[github-actions]

QVAC E2E — macos — ✅ all tests passed (98/100, 336s)

Config: suite=smoke · filter=(none) · exclude=(none)
View run · Artifacts: reports

[github-actions]

Tier-based Approval Status

**PR Tier:** TIER1

**Current Status:** ✅ APPROVED

**Requirements:**
- 1 Team Member approval ✅ (2/1)
- 1 Team Lead OR Management approval ✅ (1/1)



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*This comment is automatically updated when reviews change.*

[Victor-Rodzko]

/review