fix: retry cold ipfs proxy connects once per gateway

[erubboli]

Problem

Token icons kept disappearing intermittently even though the deployed /ipfs proxy code was correct. In-container instrumentation showed the route's upstream fetch to the production proxy failing with connect-level ETIMEDOUT well under the 12s gateway budget — and succeeding on an immediate identical retry. Cold connects from a small container to the proxy flake; the route treated a network throw the same as a gateway failure and moved on (with a single default gateway, straight to 502), so token metadata resolved to null and the UI showed letter avatars.

Fix

• Network-level throws (connect errors, aborts) are retried once on the same gateway. HTTP-level statuses are never retried — they are answers, not accidents (covered by tests).
• Moves the colocated route test out of src/pages: Astro was compiling [...path].test.ts as a phantom endpoint route importing vitest, which does not exist in production (any future /ipfs/*.test request would 500).

Tests

• retries a network-level throw on the same gateway once
• does not retry HTTP-level failures
• full suite: 70 files / 844 tests green, tsc clean, astro build OK