build(deps): move zod to 4.6.7 and lift the 4.5 hold

.github/dependabot.yml

@@ -24,17 +24,6 @@ updates:
           - "patch"
           - "minor"
     ignore:
-      # zod 4.5 made `z.iso.datetime()` require seconds, so a request carrying
-      # `2026-01-01T06:15Z` that passes today would be refused with a 422 on
-      # every route that validates a timestamp, and 4.6 rewrites nullable and
-      # primitive unions in the generated JSON Schema from `anyOf` to `type`
-      # arrays, which reshapes the OpenAPI document and every MCP tool schema.
-      # Both are contract changes for the web client, the iOS app and MCP
-      # callers, not a routine bump, so the move past 4.4 gets its own change
-      # with the timestamp producers audited. Patch releases on 4.4 still
-      # arrive.
-      - dependency-name: "zod"
-        versions: [">=4.5.0"]
       # Next 16.4.0 breaks URL state after history traversal: with a sheet
       # opened through `?doc=`, Back leaves it open, and `[` / `]` sometimes
       # do not move `?day=`. Reproduced in three end-to-end journeys (3 of 40