fix: bump Bun to 1.3.10 and harden startup for non-AVX CPUs (#213)

Bun 1.3.9 crashes with a segfault on CPUs without AVX support due to a
WASM IPInt bug (oven-sh/bun#27340), fixed in 1.3.10 via oven-sh/bun#26922.

- Bump Bun from 1.3.9 to 1.3.10 in Dockerfile, CI workflows, and packageManager
- Skip env config script when no GitHub/Gitea env vars are set
- Make startup scripts (env-config, recovery, repair) fault-tolerant so
  a crash in a non-critical script doesn't abort the entrypoint via set -e

.github/workflows/astro-build-test.yml

@@ -33,7 +33,7 @@ jobs:
       - name: Setup Bun
         uses: oven-sh/setup-bun@v1
         with:
-          bun-version: '1.3.6'
+          bun-version: '1.3.10'
 
       - name: Check lockfile and install dependencies
         run: |