Fix test tasks connecting to production DB

mise.toml's `_.file = ".env"` loads the production DATABASE_URL into
the process environment before any task runs. Deno's --env-file flag
does not override variables already present in the environment, so
both `deno task test` and `mise run migrate:test` were silently
connecting to the production database instead of the test database.

This caused local tests to see real production data (e.g. posts from
November 2025) and migrate:test to apply migrations against production
rather than hackerspub_test. CI was also affected when DATABASE_URL
was already set in the environment.

Fix by using godotenv (github:joho/godotenv) with the -o (override)
flag, which forcibly overwrites any pre-existing environment variable
with the value from .env.test regardless of how it was set.

Assisted-by: Claude Code:claude-sonnet-4-6

Author: dahlia

deno.json

@@ -214,7 +214,7 @@
       ],
       "command": "deno fmt --check && deno lint && deno check ."
     },
-    "test": "deno test --env-file=.env.test --allow-all --parallel",
+    "test": "godotenv -f .env.test -o deno test --allow-all --parallel",
     "dev": "cd web && deno task dev",
     "build": "cd web && deno task build",
     "start": "cd web && deno task start",

mise.toml

@@ -3,6 +3,7 @@ deno = "2.7.4"
 node = "24"
 pnpm = "10.12.4"
 "npm:@sentry/mcp-server" = "latest"
+"github:joho/godotenv" = "latest"
 
 [env]
 _.file = ".env"
@@ -61,7 +62,7 @@ run = "deno run -A drizzle-kit generate"
 
 [tasks."migrate:test"]
 description = "Run database migrations against the test database"
-run = "deno run --env-file=.env.test -A drizzle-kit migrate"
+run = "godotenv -f .env.test -o deno run -A drizzle-kit migrate"
 
 [tasks."keygen"]
 description = "Generate an instance actor key pair (prints a JWK to stdout)"