v0.4.0

What's Changed

• docs: living pending-items checklist by @gesparza8138 in #53
• docs: m4b plan for file sharing by @gesparza8138 in #54
• feat: signing key tooling and adapter task branch by @gesparza8138 in #55
• feat: signing key tooling and adapter task branch (take 2) by @gesparza8138 in #56
• feat: files schemas, guardrails, tools, cleanup job by @gesparza8138 in #57
• infra: files bucket, key group, files behavior, cleanup schedule by @gesparza8138 in #58
• test: files e2e against the m4b exit criteria by @gesparza8138 in #59
• docs: files guide, rotation runbook, m4b prd row by @gesparza8138 in #60
• fix: align files bucket keys with the public uri by @gesparza8138 in #61
• fix: files behavior serves uncached so revocation is immediate by @gesparza8138 in #62

Full Changelog: v0.3.0...v0.4.0