feat(kyberforge): enable codex marketplace output

Uncomment marketplace.outputs.codex in apm.yml. Codex output requires
every package to declare a category -- added one per package (Developer
Tools / Utilities / Version Control / Productivity, matching each
plugin's actual scope).

Re-running apm pack after enabling codex auto-synced 'codex' into each
local package's own targets: list (apm.yml, per plugin) -- packages
belonging to a marketplace that publishes a codex output need to declare
codex as a supported compile target for that to be coherent. Verified
idempotent: a second apm pack --check-clean run makes no further changes.

.claude-plugin/marketplace.json regenerated (now carries category per
plugin); .agents/plugins/marketplace.json is the new codex artifact.

Refs: #90

apm.yml

@@ -17,16 +17,12 @@ marketplace:
   build:
     tagPattern: "v{version}"
 
-  # Output targets (map form). 'claude' is enabled by default;
-  # uncomment 'codex' below to publish the Codex artifact too.
-  # Each output writes to its profile default path; add 'path:'
-  # under a key to override.
+  # Output targets (map form). Each output writes to its profile default
+  # path; add 'path:' under a key to override.
+  # 'codex' requires every package below to declare 'category:' (satisfied).
   outputs:
     claude: {}
-    # codex: {}
-    #
-    # Note: enabling codex requires every package below to declare
-    # 'category:' (e.g. category: Productivity).
+    codex: {}
 
   # CI tip: build one or all formats with a machine-readable manifest:
   #   apm pack --marketplace=claude,codex --json | jq -r '.marketplace.outputs[].path'
@@ -39,33 +35,40 @@ marketplace:
       description: Skills and agents for creating, maintaining, and managing a Claude Code / Copilot CLI plugin marketplace.
       source: ./plugins/kyberforge
       version: 1.4.0
+      category: Developer Tools
 
     - name: bin
       description: A place for things to be binned
       source: ./plugins/bin
       version: 1.1.1
+      category: Utilities
 
     - name: git
       description: Skills for working with Git — conventional commits, branch management, pull requests, and feature flow.
       source: ./plugins/git
       version: 1.3.2
+      category: Version Control
 
     - name: gitea
       description: Skills for managing Gitea repositories — issues, pull requests, milestones, releases, and wikis.
       source: ./plugins/gitea
       version: 1.3.3
+      category: Version Control
 
     - name: core
       description: Cross-cutting utility skills for everyday AI-assisted coding — triage, diagnosis, architecture review, and session navigation.
       source: ./plugins/core
       version: 1.1.0
+      category: Productivity
 
     - name: mattpocock-skills
       description: Skills for Real Engineers — planning, TDD, architecture, and debugging workflows from Matt Pocock's .claude directory.
       source: mattpocock/skills
       version: "^1.2.0"
+      category: Productivity
 
     - name: lint
       description: Skills and agents for configuring and running linters.
       source: ./plugins/lint
       version: 1.1.5
+      category: Developer Tools