publicTypeIndex.jsonld should be publicly readable, not owner-only #297

Problem

Pod creation currently applies generatePrivateAcl to /settings/ (owner-only, read/write/control, acl:default). This makes every file in /settings/ private — including publicTypeIndex.jsonld, which by Solid convention must be publicly readable so other agents/apps can discover what types of resources the user has.

Current behaviour

• /settings/.acl — owner only, with acl:default inheriting down
• /settings/publicTypeIndex.jsonld — inherits private → not readable by anyone but the owner
• /settings/privateTypeIndex.jsonld — inherits private ✅ (correct)

Expected behaviour

• /settings/ — owner only (preferences, private stuff) ✅
• /settings/publicTypeIndex.jsonld — public read, owner write/control
• /settings/privateTypeIndex.jsonld — owner only ✅

Fix

Write a resource-specific ACL at /settings/publicTypeIndex.jsonld.acl during pod creation that grants:

• Owner: read, write, control
• foaf:Agent (public): read

This overrides the inherited container default for that one file.

Impact

Without this, apps that try to read a user's public type index (data browsers, friend lists, contact apps, etc.) fail silently or get 403, breaking interop with the wider Solid ecosystem.

Files affected

• src/handlers/container.js — pod creation (around line 202)
• src/server.js — single-user pod creation (around line 623)