refactor: standardize naming conventions across agents, tools, and hooks

- Rename agent "OpenCode-Builder" to "opencode-builder" (kebab-case)
- Rename tool "slashcommand" to "slash_command" (snake_case)
- Add "Hook" suffix to 3 factory functions:
  - createCompactionContextInjector → createCompactionContextInjectorHook
  - createSessionNotification → createSessionNotificationHook
  - createTodoContinuationEnforcer → createTodoContinuationEnforcerHook
- Rename createCommentCheckerHooks → createCommentCheckerHook (singular)

BREAKING CHANGE: Config files using "OpenCode-Builder" must update to "opencode-builder".
BREAKING CHANGE: Agent prompts referencing "slashcommand" must update to "slash_command".

src/config/schema.ts

@@ -40,7 +40,7 @@ export const OverridableAgentNameSchema = z.enum([
   "plan",
   "sisyphus",
   "sisyphus-junior",
-  "OpenCode-Builder",
+  "opencode-builder",
   "prometheus",
   "metis",
   "momus",
@@ -136,7 +136,7 @@ export const AgentOverridesSchema = z.object({
   plan: AgentOverrideConfigSchema.optional(),
   sisyphus: AgentOverrideConfigSchema.optional(),
   "sisyphus-junior": AgentOverrideConfigSchema.optional(),
-  "OpenCode-Builder": AgentOverrideConfigSchema.optional(),
+  "opencode-builder": AgentOverrideConfigSchema.optional(),
   prometheus: AgentOverrideConfigSchema.optional(),
   metis: AgentOverrideConfigSchema.optional(),
   momus: AgentOverrideConfigSchema.optional(),