feat: ESCALATE verdict, issue tracker, onboarding commands

Add 3-verdict system (PASS/FAIL/ESCALATE) with priority handling across
simple and phased pipelines. Senior reviewers can now escalate issues
requiring human intervention, immediately breaking the review loop.

- ESCALATE verdict extraction with highest priority over PASS/FAIL
- Issue Tracker tables (ISS-NNN) carried across iterations
- Auto-escalate heuristic using (file, keyword) composite fingerprints
- Report restructuring: executive view first (verdict → tracker → metrics)
- Onboarding: `doctor`, `demo`, `init --guided` commands
- Exit codes: PASS=0, FAIL=1, ESCALATE=2
- 87 tests passing (54 config + 25 onboarding + 8 integration)

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

cross_eval/models.py

@@ -24,7 +24,7 @@ class StepConfig:
 
     name: str
     agent: str  # reference to agents key
-    role: str  # "generate" or "review"
+    role: str  # "coding" or "review"
     prompt_template: str  # "default:<role>" or file path
     output_key: str
     verdict: bool = False
@@ -105,6 +105,7 @@ class IterationResult:
     phase_name: Optional[str] = None
     repeated_aggregate_warning: Optional[str] = None
     review_metrics: Optional[ReviewMetrics] = None
+    escalated_issues: Optional[str] = None
 
 
 @dataclass
@@ -116,3 +117,4 @@ class PipelineResult:
     total_duration: float = 0.0
     run_dir: Optional[Path] = None
     repeated_aggregate_warnings: list[str] = field(default_factory=list)
+    escalated_issues: list[str] = field(default_factory=list)