refactor: migrate plugins to Claude Code spec format

- Move plugin manifests from .github/plugin/ to .claude-plugin/
- Convert items[] to Claude Code spec fields (agents, commands, skills)
- Rename tags to keywords, drop display/featured/instructions from plugins
- Delete all symlinks and materialized files from plugin directories
- Add eng/materialize-plugins.mjs to copy source files into plugin dirs at publish time
- Add .github/workflows/publish.yml for staged->main publishing
- Update CI triggers to target staged branch
- Update validation, creation, marketplace, and README generation scripts
- Update CONTRIBUTING.md and AGENTS.md documentation
- Include all new content from main (polyglot-test-agent, gem-browser-tester,
  fabric-lakehouse, fluentui-blazor, quasi-coder, transloadit-media-processing,
  make-repo-contribution hardening, website logo/gradient changes)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

plugins/project-planning/.github/plugin/plugin.json

@@ -7,7 +7,7 @@
   },
   "repository": "https://github.com/github/awesome-copilot",
   "license": "MIT",
-  "tags": [
+  "keywords": [
     "planning",
     "project-management",
     "epic",
@@ -17,78 +17,23 @@
     "architecture",
     "technical-spike"
   ],
-  "display": {
-    "ordering": "alpha",
-    "show_badge": true
-  },
-  "items": [
-    {
-      "path": "agents/task-planner.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "agents/task-researcher.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "agents/planner.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "agents/plan.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "agents/prd.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "agents/implementation-plan.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "agents/research-technical-spike.agent.md",
-      "kind": "agent"
-    },
-    {
-      "path": "instructions/task-implementation.instructions.md",
-      "kind": "instruction"
-    },
-    {
-      "path": "instructions/spec-driven-workflow-v1.instructions.md",
-      "kind": "instruction"
-    },
-    {
-      "path": "prompts/breakdown-feature-implementation.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/breakdown-feature-prd.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/breakdown-epic-arch.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/breakdown-epic-pm.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/create-implementation-plan.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/update-implementation-plan.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/create-github-issues-feature-from-implementation-plan.prompt.md",
-      "kind": "prompt"
-    },
-    {
-      "path": "prompts/create-technical-spike.prompt.md",
-      "kind": "prompt"
-    }
+  "agents": [
+    "./agents/task-planner.md",
+    "./agents/task-researcher.md",
+    "./agents/planner.md",
+    "./agents/plan.md",
+    "./agents/prd.md",
+    "./agents/implementation-plan.md",
+    "./agents/research-technical-spike.md"
+  ],
+  "commands": [
+    "./commands/breakdown-feature-implementation.md",
+    "./commands/breakdown-feature-prd.md",
+    "./commands/breakdown-epic-arch.md",
+    "./commands/breakdown-epic-pm.md",
+    "./commands/create-implementation-plan.md",
+    "./commands/update-implementation-plan.md",
+    "./commands/create-github-issues-feature-from-implementation-plan.md",
+    "./commands/create-technical-spike.md"
   ]
 }

plugins/project-planning/agents/implementation-plan.md

@@ -1 +0,0 @@
-../../../agents/implementation-plan.agent.md

plugins/project-planning/agents/plan.md

@@ -1 +0,0 @@
-../../../agents/plan.agent.md

plugins/project-planning/agents/planner.md

@@ -1 +0,0 @@
-../../../agents/planner.agent.md

plugins/project-planning/agents/prd.md

@@ -1 +0,0 @@
-../../../agents/prd.agent.md

plugins/project-planning/agents/research-technical-spike.md

@@ -1 +0,0 @@
-../../../agents/research-technical-spike.agent.md

plugins/project-planning/agents/task-planner.md

@@ -1 +0,0 @@
-../../../agents/task-planner.agent.md

plugins/project-planning/agents/task-researcher.md

@@ -1 +0,0 @@
-../../../agents/task-researcher.agent.md

plugins/project-planning/commands/breakdown-epic-arch.md

@@ -1 +0,0 @@
-../../../prompts/breakdown-epic-arch.prompt.md

plugins/project-planning/commands/breakdown-epic-pm.md

@@ -1 +0,0 @@
-../../../prompts/breakdown-epic-pm.prompt.md

plugins/project-planning/commands/breakdown-feature-implementation.md

@@ -1 +0,0 @@
-../../../prompts/breakdown-feature-implementation.prompt.md

plugins/project-planning/commands/breakdown-feature-prd.md

@@ -1 +0,0 @@
-../../../prompts/breakdown-feature-prd.prompt.md

plugins/project-planning/commands/create-github-issues-feature-from-implementation-plan.md

@@ -1 +0,0 @@
-../../../prompts/create-github-issues-feature-from-implementation-plan.prompt.md

plugins/project-planning/commands/create-implementation-plan.md

@@ -1 +0,0 @@
-../../../prompts/create-implementation-plan.prompt.md

plugins/project-planning/commands/create-technical-spike.md

@@ -1 +0,0 @@
-../../../prompts/create-technical-spike.prompt.md

plugins/project-planning/commands/update-implementation-plan.md

@@ -1 +0,0 @@
-../../../prompts/update-implementation-plan.prompt.md