feat: [gem-team] Add confidence metric, optimize planner workflow (#1695)

* feat: add explicit assumption rule and confidence metric to agent documentation

- Add `confidence` field (0‑1) to the output schema in `agents/gem-browser-tester.agent.md`
- Include `confidence` in the `extra` object of `agents/gem-devops.agent.md`
- Append the guideline “State assumptions explicitly; never guess silently” to all agent docs
- Update the “Bisect (Complex Only)” heading to reflect its gate condition
- Minor wording and formatting adjustments across the affected agent documents

* chore: update readme

* chore(release): Streamline agent documentation sections (remove self‑critique steps, renumber Handle Failure/Output)

agents/gem-mobile-tester.agent.md

@@ -146,18 +146,13 @@ For each platform in task_definition.platforms:
 - Frame rate: iOS (Core Animation FPS), Android (`adb shell dumpsys gfxstats`)
 - Bundle size (JS/Flutter)
 
-### 6. Self-Critique
-
-- Check: all tests passed, zero crashes
-- Skip: performance, device farm — covered by integration check
-
-### 7. Handle Failure
+### 6. Handle Failure
 
 - Capture evidence (screenshots, videos, logs, crash reports)
 - Classify: transient (retry) | flaky (mark, log) | regression (escalate) | platform_specific | new_failure
 - Log failures, retry: 3x exponential backoff
 
-### 8. Error Recovery
+### 7. Error Recovery
 
 | Error                  | Recovery                                                                            |
 | ---------------------- | ----------------------------------------------------------------------------------- |
@@ -166,13 +161,13 @@ For each platform in task_definition.platforms:
 | Android build fail     | Check Gradle, `./gradlew clean`, rebuild                                            |
 | Simulator unresponsive | iOS: `xcrun simctl shutdown all && xcrun simctl boot all` / Android: `adb emu kill` |
 
-### 9. Cleanup
+### 8. Cleanup
 
 - Stop Metro if started
 - Close simulators/emulators if opened
 - Clear artifacts if `cleanup = true`
 
-### 10. Output
+### 9. Output
 
 Return JSON per `Output Format`
 </workflow>
@@ -246,6 +241,7 @@ Return JSON per `Output Format`
   "extra": {
     "execution_details": { "platforms_tested": ["ios", "android"], "framework": "string", "tests_total": "number", "time_elapsed": "string" },
     "test_results": { "ios": { "total": "number", "passed": "number", "failed": "number", "skipped": "number" }, "android": {...} },
+    "confidence": "number (0-1)",
     "performance_metrics": { "cold_start_ms": {...}, "memory_mb": {...}, "bundle_size_kb": "number" },
     "gesture_results": [{ "gesture_id": "string", "status": "passed|failed", "platform": "string" }],
     "push_notification_results": [{ "scenario_id": "string", "status": "passed|failed", "platform": "string" }],
@@ -288,6 +284,7 @@ Return JSON per `Output Format`
 - NEVER skip app lifecycle testing
 - NEVER test simulator only if device farm required
 - Always use established library/framework patterns
+- State assumptions explicitly; never guess silently
 
 ### I/O Optimization