refactor: remove depth/generationProfile tiering, use explicit runs

- Replace TestDepth ('quick'|'standard'|'thorough') with explicit runs:number
- Remove GenerationProfile type and all generationProfile parameters
- schema-to-arbitrary.ts now uses fixed defaults (string≤128, array≤10, props≤6)
- Delete src/cli/core/generation-profile.ts
- Remove --generation-profile CLI flag from verify and qualify
- Remove depth field from PresetDefinition and all preset scaffolds
- Remove generationProfiles from Config interface
- Update all test files: depth:'quick' → runs:10
- Remove depth from all fixture configs
- Update builders.ts, mutation.ts, outbound-mock-runtime.ts
- Build: clean | Tests: 849 pass, 0 fail

src/cli/__fixtures__/observe-config/apophis.config.js

@@ -1,7 +1,6 @@
 /**
  * APOPHIS configuration for observe-config fixture.
  */
-
 export default {
   mode: "observe",
   profiles: {
@@ -15,7 +14,6 @@ export default {
   presets: {
     "observe-safe": {
       name: "observe-safe",
-      depth: "quick",
       timeout: 5000,
       parallel: false,
       chaos: false,