DX-5383: Add AGENTS.md, Cursor rules, and agent skills

[harshitha-cstk]

Summary

Adds AI agent guidance at the repo root for @contentstack/marketplace-sdk.

Changes

• AGENTS.md — Entry point: product scope (Marketplace / Developer Hub, not CDA), tech stack from package.json, lib/ layout, commands, sanity/env notes, links to rules and skills.
• .cursor/rules/ — README.md index plus rules: dev workflow, JavaScript conventions, Marketplace SDK patterns, testing, always-on code review.
• skills/ — README plus skills: code-review, testing, contentstack-javascript-marketplace, framework (HTTP layer).

Refs: DX-5383

[github-actions]

🔒 Security Scan Results

ℹ️ Note: Only vulnerabilities with available fixes (upgrades or patches) are counted toward thresholds.

Check Type	Count (with fixes)	Without fixes	Threshold	Result
🔴 Critical Severity	0	0	10	✅ Passed
🟠 High Severity	0	0	25	✅ Passed
🟡 Medium Severity	0	0	500	✅ Passed
🔵 Low Severity	0	0	1000	✅ Passed

⏱️ SLA Breach Summary

✅ No SLA breaches detected. All vulnerabilities are within acceptable time thresholds.

Severity	Breaches (with fixes)	Breaches (no fixes)	SLA Threshold (with/no fixes)	Status
🔴 Critical	0	0	15 / 30 days	✅ Passed
🟠 High	0	0	30 / 120 days	✅ Passed
🟡 Medium	0	0	90 / 365 days	✅ Passed
🔵 Low	0	0	180 / 365 days	✅ Passed

✅ BUILD PASSED - All security checks passed

[github-actions]

Coverage report for commit: b967727
File: coverage/clover.xml

Cover ┌─────────────────────────┐ Freq.
   0% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  10% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  20% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  30% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  40% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  50% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  60% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  70% │ ███░░░░░░░░░░░░░░░░░░░░ │  5.3%
  80% │ ███████████████████████ │ 47.4%
  90% │ ████████░░░░░░░░░░░░░░░ │ 15.8%
 100% │ ████████████████░░░░░░░ │ 31.6%
      └─────────────────────────┘
 *Legend:* █ = Current Distribution 

Summary - Lines: 85.93% | Methods: 96.08% | Branches: 67.22%

Files	Lines	Methods	Branches
lib
contentstack.js	100.00%	100.00%	100.00%
contentstackClient.js	100.00%	100.00%	85.29%
contentstackCollection.js	86.67%	100.00%	90.00%
entity.js	75.31%	100.00%	53.45%
lib/core
Util.js	96.36%	100.00%	83.64%
concurrency-queue.js	90.40%	90.91%	83.74%
contentstackError.js	100.00%	100.00%	100.00%
contentstackHTTPClient.js	100.00%	100.00%	94.59%
messageHandler.js	66.67%	57.14%	60.00%
region.js	100.00%	100.00%	75.00%
lib/marketplace/app/hosting
deployment.js	80.88%	100.00%	63.16%
index.js	80.00%	100.00%	58.23%
lib/marketplace/app
index.js	80.46%	90.00%	53.26%
lib/marketplace/app/oauth
index.js	83.33%	100.00%	52.63%
lib/marketplace/apprequest
index.js	82.86%	100.00%	58.54%
lib/marketplace/authorization
index.js	83.33%	100.00%	65.12%
lib/marketplace
index.js	90.48%	100.00%	82.76%
lib/marketplace/installation
index.js	81.82%	100.00%	56.52%
lib/marketplace/installation/webhooks
index.js	81.58%	100.00%	53.19%

_{🤖 comment via lucassabreu/comment-coverage-clover}

[github-actions]

🔒 Security Scan Results

ℹ️ Note: Only vulnerabilities with available fixes (upgrades or patches) are counted toward thresholds.

Check Type	Count (with fixes)	Without fixes	Threshold	Result
🔴 Critical Severity	0	0	10	✅ Passed
🟠 High Severity	0	0	25	✅ Passed
🟡 Medium Severity	0	0	500	✅ Passed
🔵 Low Severity	0	0	1000	✅ Passed

⏱️ SLA Breach Summary

✅ No SLA breaches detected. All vulnerabilities are within acceptable time thresholds.

Severity	Breaches (with fixes)	Breaches (no fixes)	SLA Threshold (with/no fixes)	Status
🔴 Critical	0	0	15 / 30 days	✅ Passed
🟠 High	0	0	30 / 120 days	✅ Passed
🟡 Medium	0	0	90 / 365 days	✅ Passed
🔵 Low	0	0	180 / 365 days	✅ Passed

✅ BUILD PASSED - All security checks passed

[github-actions]

🔒 Security Scan Results

ℹ️ Note: Only vulnerabilities with available fixes (upgrades or patches) are counted toward thresholds.

Check Type	Count (with fixes)	Without fixes	Threshold	Result
🔴 Critical Severity	0	0	10	✅ Passed
🟠 High Severity	0	0	25	✅ Passed
🟡 Medium Severity	0	0	500	✅ Passed
🔵 Low Severity	0	0	1000	✅ Passed

⏱️ SLA Breach Summary

✅ No SLA breaches detected. All vulnerabilities are within acceptable time thresholds.

Severity	Breaches (with fixes)	Breaches (no fixes)	SLA Threshold (with/no fixes)	Status
🔴 Critical	0	0	15 / 30 days	✅ Passed
🟠 High	0	0	30 / 120 days	✅ Passed
🟡 Medium	0	0	90 / 365 days	✅ Passed
🔵 Low	0	0	180 / 365 days	✅ Passed

✅ BUILD PASSED - All security checks passed