feat: Add template system with testing showcase

Implements template-based project creation allowing teams to start with
professional example code instead of empty projects.

Features:
- Two templates: 'basic' (minimal) and 'testing' (45-test showcase)
- Template variable substitution ({{PROJECT_NAME}}, etc.)
- Template validation with helpful error messages
- `weevil new --list-templates` command
- Templates embedded in binary at compile time

Testing template includes:
- 3 complete subsystems (MotorCycler, WallApproach, TurnController)
- Hardware abstraction layer with mock implementations
- 45 comprehensive tests (unit, integration, system)
- Professional documentation (DESIGN_AND_TEST_PLAN.md, etc.)

Usage:
  weevil new my-robot                    # basic template
  weevil new my-robot --template testing # testing showcase
  weevil new --list-templates            # show available templates

This enables FTC teams to learn from working code and best practices
rather than starting from scratch.

All 62 tests passing.

templates/testing/build.gradle.template

@@ -0,0 +1,62 @@
+// Build configuration for {{PROJECT_NAME}}
+// This file is managed by the FTC SDK
+
+buildscript {
+    repositories {
+        mavenCentral()
+        google()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:8.1.0'
+    }
+}
+
+apply plugin: 'com.android.application'
+
+android {
+    namespace 'org.firstinspires.ftc.{{PACKAGE_NAME}}'
+    compileSdk 34
+
+    defaultConfig {
+        applicationId 'org.firstinspires.ftc.{{PACKAGE_NAME}}'
+        minSdk 24
+        //noinspection ExpiredTargetSdkVersion
+        targetSdk 28
+        
+        versionCode 1
+        versionName "1.0"
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    sourceSets {
+        main {
+            java {
+                srcDir 'src/main/java'
+            }
+        }
+        test {
+            java {
+                srcDir 'src/test/java'
+            }
+        }
+    }
+}
+
+repositories {
+    mavenCentral()
+    google()
+}
+
+dependencies {
+    implementation 'org.firstinspires.ftc:RobotCore:10.1.1'
+    implementation 'org.firstinspires.ftc:Hardware:10.1.1'
+    implementation 'org.firstinspires.ftc:FtcCommon:10.1.1'
+    implementation 'androidx.appcompat:appcompat:1.6.1'
+
+    testImplementation 'junit:junit:4.13.2'
+    testImplementation 'org.mockito:mockito-core:5.3.1'
+}