refactor: rename OhMyOpenCode types to OhMyOpenAgent and centralize PACKAGE_NAME

- Rename all PascalCase types: OhMyOpenCodePlugin → OhMyOpenAgentPlugin, etc.
- 231 OhMyOpenAgent references across ~60 files
- Centralize 4 PACKAGE_NAME constants to import from plugin-identity.ts
- Update src/plugin-config.ts to use CONFIG_BASENAME from plugin-identity

Wave 3 Tasks 5 & 6 complete.

src/plugin/skill-context.ts

@@ -1,5 +1,5 @@
 import type { AvailableSkill } from "../agents/dynamic-agent-prompt-builder"
-import type { OhMyOpenCodeConfig } from "../config"
+import type { OhMyOpenAgentConfig } from "../config"
 import type { BrowserAutomationProvider } from "../config/schema/browser-automation"
 import type {
   LoadedSkill,
@@ -49,7 +49,7 @@ function filterProviderGatedSkills(
 
 export async function createSkillContext(args: {
   directory: string
-  pluginConfig: OhMyOpenCodeConfig
+  pluginConfig: OhMyOpenAgentConfig
 }): Promise<SkillContext> {
   const { directory, pluginConfig } = args