Add AgentPay x402 extension to community catalog

Add pay-x402 extension submitted by @shawnhvac to:
- extensions/catalog.community.json (alphabetical order)
- docs/community/extensions.md community extensions table

Closes #2632

Assisted-by: GitHub Copilot (model: claude-sonnet-5, autonomous)
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: dhruv-15-03

docs/community/extensions.md

@@ -27,6 +27,7 @@ The following community-contributed extensions are available in [`catalog.commun
 |-----------|---------|----------|--------|-----|
 | Agent Assign | Assign specialized Claude Code agents to spec-kit tasks for targeted execution | `process` | Read+Write | [spec-kit-agent-assign](https://github.com/xymelon/spec-kit-agent-assign) |
 | Agent Governance | Generate agent-platform repository governance files from Spec Kit metadata | `process` | Read+Write | [spec-kit-agent-governance](https://github.com/bigsmartben/spec-kit-agent-governance) |
+| AgentPay x402 — Spend Controls for Spec Kit Agents | Set USDC spending caps and execute x402 payments to paid APIs during spec implementation. Zero platform fee on Base L2 | `integration` | Read+Write | [spec-kit-pay-x402](https://github.com/shawnhvac/spec-kit-pay-x402) |
 | AI-Driven Engineering (AIDE) | A structured 7-step workflow for building new projects from scratch with AI assistants — from vision through implementation | `process` | Read+Write | [aide](https://github.com/mnriem/spec-kit-extensions/tree/main/aide) |
 | Analytics | Measure what your AI builds, and how much time it saves you | `visibility` | Read+Write | [spec-kit-analytics](https://github.com/Fyloss/spec-kit-analytics) |
 | API Evolve | Managed API contract evolution — breaking-change detection, semver enforcement, deprecation orchestration, and lifecycle gates across REST, GraphQL, and gRPC | `process` | Read+Write | [spec-kit-api-evolve](https://github.com/Quratulain-bilal/spec-kit-api-evolve) |

extensions/catalog.community.json

@@ -1,6 +1,6 @@
 {
   "schema_version": "1.0",
-  "updated_at": "2026-07-24T00:00:00Z",
+  "updated_at": "2026-07-25T00:00:00Z",
   "catalog_url": "https://raw.githubusercontent.com/github/spec-kit/main/extensions/catalog.community.json",
   "extensions": {
     "aide": {
@@ -2965,6 +2965,40 @@
       "created_at": "2026-07-14T00:00:00Z",
       "updated_at": "2026-07-14T00:00:00Z"
     },
+    "pay-x402": {
+      "name": "AgentPay x402 — Spend Controls for Spec Kit Agents",
+      "id": "pay-x402",
+      "description": "Set USDC spending caps and execute x402 payments to paid APIs during spec implementation. Zero platform fee on Base L2.",
+      "author": "AgentPay Team",
+      "version": "1.0.0",
+      "download_url": "https://github.com/shawnhvac/spec-kit-pay-x402/archive/refs/tags/v1.0.0.zip",
+      "repository": "https://github.com/shawnhvac/spec-kit-pay-x402",
+      "homepage": "https://x402-agent-pay.com",
+      "documentation": "https://github.com/shawnhvac/spec-kit-pay-x402#readme",
+      "changelog": "https://github.com/shawnhvac/spec-kit-pay-x402/blob/main/CHANGELOG.md",
+      "license": "MIT",
+      "category": "integration",
+      "effect": "read-write",
+      "requires": {
+        "speckit_version": ">=0.1.0"
+      },
+      "provides": {
+        "commands": 2,
+        "hooks": 1
+      },
+      "tags": [
+        "payments",
+        "x402",
+        "budget",
+        "usdc",
+        "api"
+      ],
+      "verified": false,
+      "downloads": 0,
+      "stars": 0,
+      "created_at": "2026-07-25T00:00:00Z",
+      "updated_at": "2026-07-25T00:00:00Z"
+    },
     "plan-review-gate": {
       "name": "Plan Review Gate",
       "id": "plan-review-gate",