fix(pwa): re-enable Workbox precaching (remove injectionPoint override)

[Just-Insane]

Related to closed PR #548 (fix/media-error-handling), which was split into smaller focused PRs.

Description

injectionPoint: undefined was set in vite.config.ts to silence a Workbox AssertionError about multiple self.__WB_MANIFEST occurrences (an if guard in sw.ts plus the precacheAndRoute() call = two matches; Workbox requires exactly one). The unintended consequence: Workbox never injected the precache manifest, so no assets were precached — every cold start hit the network instead of serving from cache, and offline use was broken entirely.

Fix: remove the if guard in sw.ts (leaving exactly one self.__WB_MANIFEST reference) then remove injectionPoint: undefined from vite.config.ts to restore normal precaching behaviour.

Fixes #

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings

AI disclosure:

• Partially AI assisted (clarify which code was AI assisted and briefly explain what it does).
• Fully AI generated (explain what all the generated code does in moderate detail).

The root cause diagnosis (two self.__WB_MANIFEST references causing Workbox to silently skip injection) was identified with AI assistance. I verified the fix by checking Workbox's injectionPoint behaviour and confirming precaching was restored.