feat(deno): Add Deno + Aurora DSQL samples with booking API

[pyraenix]

Add Deno runtime samples for connecting to Amazon Aurora DSQL, including a basic client/ORM sample and a real-world booking API sample application. Deno is the first new runtime added to this repository that uses a native (non-Node.js) PostgreSQL driver.

deno/deno-postgres — Basic Client/ORM Sample

Simple connect-and-query example using the native deno-postgres driver (jsr:@db/postgres) with IAM token authentication over SSL verify-full. Demonstrates concurrent queries across multiple connections. Follows the same pattern as javascript/node-postgres.

• src/example_preferred.ts — main example
• test/example_preferred.test.ts — integration test
• deno.json, deno.lock, README.md, .gitignore

deno/booking-api/deno-postgres — Booking API Sample Application

A booking/reservation REST API built with Deno.serve() and deno-postgres, backed by Aurora DSQL. Goes beyond connect-and-query to demonstrate real application patterns:

• Full CRUD: POST/GET/PUT/DELETE /bookings + GET /health
• IAM token authentication via @aws-sdk/dsql-signer
• OCC retry handling for SQLSTATE OC000 concurrency conflicts with exponential backoff + jitter
• Overlap detection for double-booking prevention within transactions (DSQL has no exclusion constraints)
• Deno least-privilege permissions model (--allow-net, --allow-env, --allow-read scoped to minimum required)
• Serverless-ready architecture (deno serve compatible, per-request connections, no mutable global state)
• UUID primary keys via gen_random_uuid() (DSQL has no sequences)
• Graceful shutdown with schema teardown on SIGINT/SIGTERM

Testing (all verified against real Aurora DSQL cluster)

• 20 property-based tests (fast-check): router dispatch, overlap detection symmetry, JSON response format, malformed JSON rejection, OCC error detection/retry/exhaustion/pass-through, token generator error formatting
• 9 integration tests: full CRUD flow against real DSQL
• 15 smoke tests (test-api.sh): health check, CRUD, overlap conflict, concurrent OCC conflict, validation errors, cleanup

Documentation

• Architecture diagram (ASCII art)
• Create booking request flow diagram
• Data model diagram
• Key design decisions table for Aurora DSQL
• API endpoints table with status codes
• Error response examples
• Deno permissions model explanation
• OCC retry behavior section
• Deno Deploy deployment instructions
• Example curl commands for all endpoints
• Project structure overview

Root README

Updated the repository root README.md to include Deno in the Client/ORM table and the booking API in the Sample Applications table.

Technical Notes

• npm:pg (node-postgres) was evaluated but does not work with Aurora DSQL from Deno due to a TLS compatibility issue in Deno's Node.js compat layer. Only the native deno-postgres driver is included.
• Authentication and cluster management samples are intentionally omitted — they are pure AWS SDK calls with no Deno-specific value, matching the pattern of TypeScript and PHP samples.

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the terms of the MIT-0 license.

Thank you for your contribution!