Use placeholder tip bot wallet in env example

[z272258483]

Summary

• replace the real-format TIP_BOT_WALLET value in .env.example with an explicit placeholder
• add a short note telling deployers to provide their own public RTC wallet address

Validation

• rg -n "TIP_BOT_WALLET|RTC[0-9a-fA-F]{40}" .env.example
• git diff --check

Closes #7483

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[Monster5860]

Reviewed the change and it looks correct to me. I checked the only indexed uses of TIP_BOT_WALLET: the example file and .github/workflows/tip-bot.yml. The workflow reads TIP_BOT_WALLET from GitHub Secrets, not from .env.example, so replacing the example value with a non-address placeholder should not affect tip-bot execution. The new comment also makes the deployment action explicit for operators and reduces the risk that someone copies a real-looking wallet value from the sample config into production by mistake.\n\nValidation performed:\n- inspected the PR diff for .env.example\n- searched repository code for TIP_BOT_WALLET usages\n- checked that the tip-bot workflow sources the value from secrets.TIP_BOT_WALLET\n\nVerdict: approve as a focused config-safety/docs change.