DC-059: mark done in BACKLOG + DC-PRODUCTION-GRADE-BACKLOG

BACKLOG.md

@@ -384,9 +384,10 @@ Tickets DC-046 through DC-049 implement pluggable auth + email magic link. Sami
 9. **VERSION bump:** when a batch of tasks is done, bump patch version in package.json + VERSION file, update CHANGELOG, tag.
 
 ### DC-059: Joi validation library — schema-based body validation middleware
-- **status:** in-progress
+- **status:** done
 - **owner:** hermes
 - **details:** Backend uses ad-hoc `if (!field) throw new ValidationError(...)` checks at every route entry point — 49 such checks across the codebase. They drift from the field semantics, allow unknown keys to flow through, and have no way to express structured types (CIDR, enum, port range). Tracked in `DC-PRODUCTION-GRADE-BACKLOG.md` as P1-1. Fix: `npm install joi@^18`, add `src/utilities/validate.js` exporting `validateBody(schema)` middleware factory + `schemas` object with reusable schemas. Apply to destructive routes: backups (schedule/restore/config), apps (deploy/restore/revert), assets (upload/logo). Add `__tests__/unit/validate.test.js` covering each schema's accept/reject/strip-unknown behaviour. Effort: ~2 hr.
 - **impact:** Closes P0-3 / P0-4 class of bugs at the schema layer instead of per-route. Prevents future routes from accepting arbitrary body fields. New routes copy-paste from `schemas.*` and get free validation.
 - **prerequisite:** None.
+- **result:** Shipped codex-graded B. New module `src/utilities/validate.js` (170 LOC) with `validateBody(schema, opts)` middleware + 9 Joi schemas. Every exported schema has direct unit tests (41 tests total) covering middleware semantics (not just schema.validate). Applied to 8 destructive routes: backups (schedule/restore/config), apps (deploy/restore/revert), assets (upload/logo). Key fixes during codex review: (1) IPv6 CIDR regex was permissive (accepted `::::/64`) — replaced with Joi's authoritative `string().ip({cidr: 'required'})`. (2) appRestore empty-body semantics broke under middleware `stripUnknown` default — replaced `Joi.object({}).max(0)` with `Joi.any().custom()` that enforces non-empty rejection even after strip. (3) appDeploy.config now uses `.unknown(true)` to preserve template-specific fields (`sslType`, `dnsType`, `plexClaimToken`) that the live frontend posts — without this, deployments would silently break. Removed redundant manual `appId` check in /backups/schedule and unused `mime` destructure in /assets/favicon. Duplicate legacy `/backups/schedule` handler (pre-existing) marked LEGACY with TODO note (Express only matches first registration). 1539/1539 Jest tests pass (was 1498, +41 new). ESLint warnings unchanged (416 total, all pre-existing).