feat(plugins): merge Skill management into plugins

electron/coding-projects/skill-registry.ts

@@ -1,7 +1,6 @@
 import { readFile, readdir } from 'node:fs/promises';
 import path from 'node:path';
 import {
-  BUNDLED_CODING_SKILL_IDS,
   type CodingSkillId,
 } from '../../shared/coding-skills';
 import type {
@@ -56,8 +55,9 @@ function selectedSkillIds(
   const selected = new Set<string>();
   for (const raw of value) {
     const id = raw.trim();
-    if (!allowed.has(id)) throw new Error(`Unknown bundled coding skill: ${id}`);
-    selected.add(id);
+    // Old project assignments are retained in project.json, but a removed or
+    // not-yet-installed provider must not break the current capability list.
+    if (allowed.has(id)) selected.add(id);
   }
   return selected;
 }
@@ -85,29 +85,21 @@ async function listSkillEntries(
 }
 
 export async function listProductCodingSkills(
-  bundledSkillsDir: string,
+  _bundledSkillsDir: string,
   selectedIds: readonly string[] = [],
   pluginSkillSources: readonly ProductCodingPluginSkillSource[] = [],
 ): Promise<ProductCodingSkill[]> {
   const pluginIds = pluginSkillSources.map(({ id }) => id);
-  const allIds = [...BUNDLED_CODING_SKILL_IDS, ...pluginIds];
+  const allIds = [...pluginIds];
   if (new Set(allIds).size !== allIds.length) {
     throw new Error('Duplicate coding skill identifier');
   }
   const selected = selectedSkillIds(selectedIds, allIds);
-  const sources: ProductCodingPluginSkillSource[] = [
-    ...BUNDLED_CODING_SKILL_IDS.map((id) => ({
-      id,
-      directory: path.join(bundledSkillsDir, id),
-    })),
-    ...pluginSkillSources,
-  ];
+  const sources: ProductCodingPluginSkillSource[] = [...pluginSkillSources];
   const visibleSources = sources.filter(({ id, available }) => available !== false || selected.has(id));
   return await Promise.all(visibleSources.map(async ({ id, directory, entryPath, available = true }) => {
     const sourceLocation = path.resolve(directory);
-    const location = (BUNDLED_CODING_SKILL_IDS as readonly string[]).includes(id)
-      ? path.posix.join('resources', 'coding-skills', id)
-      : sourceLocation;
+    const location = sourceLocation;
     const content = await readFile(path.join(sourceLocation, entryPath ?? 'SKILL.md'), 'utf8');
     return {
       id: productSkillId(id),