chore: remove Replit/homegit references for public GitHub repo

- Simplify dev script (drop Replit-specific env vars)
- Remove REPLIT_* fallbacks from scripts/build.js
- Rewrite root README for GitHub (local build, no EAS, no homegit URLs)
- Update clone URL in artifacts README → GitHub
- Remove replit.md (Replit workspace descriptor, no longer needed)
- Untrack scripts/push-to-gitea.sh (internal-only, added to .gitignore)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/push-to-gitea.sh

@@ -1,25 +0,0 @@
-#!/bin/bash
-set -euo pipefail
-
-GITEA_HOST="homegit.gyozamancave.fr"
-GITEA_USER="billisdead"
-GITEA_REPO="Postiz-android"
-GITEA_REMOTE_NAME="gitea"
-GITEA_REMOTE_URL="https://${GITEA_HOST}/${GITEA_USER}/${GITEA_REPO}.git"
-
-if [ -z "${GITEA_SSH_KEY:-}" ]; then
-  echo "Error: GITEA_SSH_KEY environment variable is not set. Add the Gitea API token as a Replit secret named GITEA_SSH_KEY." >&2
-  exit 1
-fi
-
-if git remote get-url "$GITEA_REMOTE_NAME" &>/dev/null; then
-  git remote set-url "$GITEA_REMOTE_NAME" "$GITEA_REMOTE_URL"
-else
-  git remote add "$GITEA_REMOTE_NAME" "$GITEA_REMOTE_URL"
-  echo "Added remote '$GITEA_REMOTE_NAME'."
-fi
-
-echo "Pushing main branch to Gitea..."
-git -c "http.extraHeader=Authorization: token ${GITEA_SSH_KEY}" \
-  push --force "$GITEA_REMOTE_NAME" main
-echo "Push to Gitea complete."