fix: fall back to app for non-asset dotted paths

[OXeu]

Summary

• simplify fetch routing for dotted paths by trying static assets first and falling back to the app when the asset is missing
• remove the explicit public route allowlist for blob handling
• add runtime tests for both the asset-hit and asset-miss cases

Verification

• cd server && bun run test
• cd server && bun run check
• cd client && bun run test
• cd client && bun run check
• cd client && bun run build
• bun run check
• bun run format:check

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