fix: enforce directory param in skill resolution, replace legacy k2p5 model ID

- Make directory required in SkillLoadOptions, getAllSkills, and async
  skill template resolvers to prevent unsafe process.cwd() fallback
- Remove dead skill export and process.cwd() fallback in skill tool
- Replace kimi-for-coding/k2p5 with kimi-for-coding/kimi-k2.5 in
  council-members-generator

src/features/opencode-skill-loader/skill-resolution-options.ts

@@ -4,6 +4,6 @@ export interface SkillResolutionOptions {
 	gitMasterConfig?: GitMasterConfig
 	browserProvider?: BrowserAutomationProvider
 	disabledSkills?: Set<string>
-	/** Project directory to discover project-level skills from. Falls back to process.cwd() if not provided. */
+	/** Project directory to discover project-level skills from. Required for async resolution — process.cwd() is unsafe in OpenCode. */
 	directory?: string
 }