feat(orchestrator): file-based orchestrator request watcher (§14.3)

- domain: OrchestratorRequest/Command parse-don't-validate + OrchestratorRequestProcessed event
- application: OrchestratorService dispatching spawn/stop/update_agent_context
- infrastructure: request watcher over .ideai/requests/, writes .response.json
- app-tauri: relay OrchestratorRequestProcessed to the frontend DTO

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/application/src/lib.rs

@@ -16,6 +16,7 @@ pub mod error;
 pub mod git;
 pub mod health;
 pub mod layout;
+pub mod orchestrator;
 pub mod project;
 pub mod remote;
 pub mod template;
@@ -33,6 +34,7 @@ pub use agent::{
     SaveProfileInput, SaveProfileOutput, UpdateAgentContext, UpdateAgentContextInput,
 };
 pub use error::AppError;
+pub use orchestrator::{OrchestratorOutcome, OrchestratorService};
 pub use git::{
     GitBranches, GitBranchesInput, GitBranchesOutput, GitCheckout, GitCheckoutInput, GitCommit,
     GitCommitInput, GitCommitOutput, GitGraph, GitGraphInput, GitGraphOutput, GitInit, GitInitInput,