refactor: wave 1 - extract leaf modules, rename catch-all files, split index.ts hooks

- Split 25+ index.ts files into hook.ts + extracted modules
- Rename all catch-all utils.ts/helpers.ts to domain-specific names
- Split src/tools/lsp/ into ~15 focused modules
- Split src/tools/delegate-task/ into ~18 focused modules
- Separate shared types from implementation
- 155 files changed, 60+ new files created
- All typecheck clean, 61 tests pass

src/agents/builtin-agents/available-skills.ts

@@ -0,0 +1,35 @@
+import type { AvailableSkill } from "../dynamic-agent-prompt-builder"
+import type { BrowserAutomationProvider } from "../../config/schema"
+import type { LoadedSkill, SkillScope } from "../../features/opencode-skill-loader/types"
+import { createBuiltinSkills } from "../../features/builtin-skills"
+
+function mapScopeToLocation(scope: SkillScope): AvailableSkill["location"] {
+  if (scope === "user" || scope === "opencode") return "user"
+  if (scope === "project" || scope === "opencode-project") return "project"
+  return "plugin"
+}
+
+export function buildAvailableSkills(
+  discoveredSkills: LoadedSkill[],
+  browserProvider?: BrowserAutomationProvider,
+  disabledSkills?: Set<string>
+): AvailableSkill[] {
+  const builtinSkills = createBuiltinSkills({ browserProvider, disabledSkills })
+  const builtinSkillNames = new Set(builtinSkills.map(s => s.name))
+
+  const builtinAvailable: AvailableSkill[] = builtinSkills.map((skill) => ({
+    name: skill.name,
+    description: skill.description,
+    location: "plugin" as const,
+  }))
+
+  const discoveredAvailable: AvailableSkill[] = discoveredSkills
+    .filter(s => !builtinSkillNames.has(s.name))
+    .map((skill) => ({
+      name: skill.name,
+      description: skill.definition.description ?? "",
+      location: mapScopeToLocation(skill.scope),
+    }))
+
+  return [...builtinAvailable, ...discoveredAvailable]
+}