feat(hot-runner): implement hot runner protocol with registry, health monitoring, and job dispatch (#791)

Adds persistent Unity editor instance support to reduce build iteration time
by eliminating cold-start overhead. Includes:

- HotRunnerTypes: interfaces for config, status, job request/result, transport
- HotRunnerRegistry: in-memory runner management with file-based persistence
- HotRunnerHealthMonitor: periodic health checks, idle recycling, job-count recycling
- HotRunnerDispatcher: job routing with wait-for-runner, timeout, and output streaming
- HotRunnerService: high-level API integrating registry, health, and dispatch
- 34 unit tests covering registration, filtering, health, dispatch, timeout, fallback
- action.yml inputs for hot runner configuration (7 new inputs)
- Input/BuildParameters integration for hot runner settings
- index.ts wiring with cold-build fallback when hot runner unavailable

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: frostebite

action.yml

@@ -182,8 +182,8 @@ inputs:
     required: false
     default: ''
     description:
-      '[Orchestrator] Run a custom job instead of the standard build automation for orchestrator (in yaml format with the
-      keys image, secrets (name, value object array), command line string)'
+      '[Orchestrator] Run a custom job instead of the standard build automation for orchestrator (in yaml format with
+      the keys image, secrets (name, value object array), command line string)'
   awsStackName:
     default: 'game-ci'
     required: false
@@ -280,6 +280,35 @@ inputs:
       '[Orchestrator] Specifies the repo for the unity builder. Useful if you forked the repo for testing, features, or
       fixes.'
 
+  hotRunnerEnabled:
+    description: '[HotRunner] Use persistent hot runner for builds (requires pre-registered runners)'
+    required: false
+    default: 'false'
+  hotRunnerTransport:
+    description: '[HotRunner] Transport protocol for hot runner communication: websocket, grpc, named-pipe'
+    required: false
+    default: 'websocket'
+  hotRunnerHost:
+    description: '[HotRunner] Hot runner host address'
+    required: false
+    default: 'localhost'
+  hotRunnerPort:
+    description: '[HotRunner] Hot runner port number'
+    required: false
+    default: '9090'
+  hotRunnerHealthInterval:
+    description: '[HotRunner] Health check interval in seconds'
+    required: false
+    default: '30'
+  hotRunnerMaxIdle:
+    description: '[HotRunner] Maximum idle time in seconds before recycling runner'
+    required: false
+    default: '3600'
+  hotRunnerFallbackToCold:
+    description: '[HotRunner] Fall back to cold build if no hot runner available'
+    required: false
+    default: 'true'
+
 outputs:
   volume:
     description: 'The Persistent Volume (PV) where the build artifacts have been stored by Kubernetes'