fix(s3): drop {env, _} tag from access_key/secret_key

[Taure]

Summary

The S3 adapter's access_key and secret_key accepted a tagged tuple {env, "VAR"} to look up credentials from the OS environment. Tagged-tuple config keys are uncommon in Erlang and added a small DSL with no benefit over passing the env-var name directly.

Change

- access_key => {env, "S3_ACCESS_KEY"},
- secret_key => {env, "S3_SECRET_KEY"}
+ access_key => "S3_ACCESS_KEY",
+ secret_key => "S3_SECRET_KEY"

The adapter resolves the name to its env-var value at store-init time. Same lazy-lookup semantics, simpler config shape.

Breaking?

Technically yes for anyone on v0.1.0, but the lib is hours old with no consumers. Tagging v0.1.1 after merge.

Test plan

• rebar3 compile clean
• rebar3 ct — 16/16 pass
• rebar3 dialyzer clean
• rebar3 xref clean
• rebar3 fmt --check clean

[github-actions]

ℹ️ 15 OTP CVEs auto-ignored (already fixed in running version)

These CVEs are patched in the installed OTP version but NVD data
has not been updated to reflect this. They are excluded from the
scan via an auto-generated .trivyignore.

CVE	Details
CVE-2026-32147	Fixed in 28.4.3, running 28.5 — Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') in SFTP chroot
CVE-2026-28808	Fixed in 28.4.2, running 28.5 — ScriptAlias CGI targets bypass directory auth (mod_auth vs mod_cgi path mismatch)
CVE-2026-32144	Fixed in 28.4.2, running 28.5 — OCSP designated-responder authorization bypass — missing signature verification (RFC 6960 §4.2.2.2)
CVE-2026-28810	Fixed in 28.4.2, running 28.5 — Predictable DNS Transaction IDs Enable Cache Poisoning in Built-in Resolver
CVE-2026-23943	Fixed in 28.4.1, running 28.5 — Pre-auth SSH DoS via unbounded zlib inflate
CVE-2026-23942	Fixed in 28.4.1, running 28.5 — SFTP root escape via component-agnostic prefix check in ssh_sftpd
CVE-2026-23941	Fixed in 28.4.1, running 28.5 — Request smuggling via first-wins Content-Length parsing in inets httpd
CVE-2026-21620	Fixed in 28.3.2, running 28.5 — TFTP Path Traversal
CVE-2016-1000107	Fixed in 28.0.4, running 28.5 — Httpd CGI Scripts Environment Variable Pollution AKA "httpoxy"
CVE-2025-58050	Fixed in 28.0.3, running 28.5 — Buffer Read Overflow on Regular Expressions with (*scs:) and (*ACCEPT)
CVE-2025-48038	Fixed in 28.0.3, running 28.5 — SSH Unverified File Handles can Cause Excessive Use of System Resources
CVE-2025-48039	Fixed in 28.0.3, running 28.5 — SSH Unverified Paths can Cause Excessive Use of System Resources
CVE-2025-48040	Fixed in 28.0.3, running 28.5 — SSH Malicious Key Exchange Messages may Lead to Excessive Resource Consumption
CVE-2025-48041	Fixed in 28.0.3, running 28.5 — SSH_FXP_OPENDIR may Lead to Exhaustion of File Handles
CVE-2025-4748	Fixed in 28.0.1, running 28.5 — Absolute Path in Zip Module