feat(pki): add slack webhook to alerts

[saifsmailbox98]

Context

This adds slack webhook to PKI alerts, earlier we only had emails and general webhooks.

Screenshots

Steps to verify the change

Add a slack webhook url to a new PKI alert

Type

• Fix
• Feature
• Improvement
• Breaking
• Docs
• Chore

Checklist

• Title follows the conventional commit format: type(scope): short description (scope is optional, e.g., fix: prevent crash on sync or fix(api): handle null response).
• Tested locally
• Updated docs (if needed)
• Read the contributing guide

[greptile-apps]

Greptile Overview

Greptile Summary

This PR adds Slack webhook integration to PKI alerts, allowing notifications to be sent to Slack channels alongside existing email and webhook channels.

Key Changes:

• Added buildSlackPayload function to format certificate expiration alerts with color-coded urgency (red for <7 days, yellow otherwise)
• Implemented triggerSlackWebhook with proper error handling and URL path masking in logs
• Added SSRF protection via blockLocalAndPrivateIpAddresses before making webhook requests
• Added hostname validation in Zod schemas to ensure URLs are from hooks.slack.com
• Updated frontend UI to include Slack channel option with proper form validation
• Documentation updated to explain Slack webhook setup

Security Measures:

• Webhook URL hostname validated to be exactly hooks.slack.com (prevents DNS rebinding attacks)
• SSRF protection blocks requests to private/internal IPs
• Webhook URL paths masked in logs to avoid exposing secret tokens
• HTTPS enforced for all Slack webhook URLs

All previously reported issues have been addressed by the developer.

Confidence Score: 5/5

• This PR is safe to merge with no blocking issues
• The implementation follows security best practices with proper SSRF protection, URL validation, and secret masking. All previously identified security concerns have been addressed. The code is well-structured and consistent with existing patterns.
• No files require special attention

Important Files Changed

Filename	Overview
backend/src/services/pki-alert-v2/pki-alert-v2-notification-fns.ts	Added Slack webhook notification functions with proper URL masking for security
backend/src/services/pki-alert-v2/pki-alert-v2-service.ts	Integrated Slack channel with SSRF protection via blockLocalAndPrivateIpAddresses
backend/src/services/pki-alert-v2/pki-alert-v2-types.ts	Added Slack config schema with hostname validation to prevent SSRF attacks
frontend/src/views/PkiAlertsV2Page/components/CreatePkiAlertV2FormSteps.tsx	Added Slack channel UI with proper form controls and display formatting

[greptile-apps]

_{4 files reviewed, 4 comments}

_{Edit Code Review Agent Settings | Greptile}

[maidul98]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scanner	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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[saifsmailbox98]

@greptile review