Add reporting, retry lifecycle, and dry-run functionality

[timkpaine]

Introduce a structured reporting layer that captures evaluation metadata, timing, topology, retries, and failures without consuming result payloads, mirroring the existing evaluator/policy architecture.

• ReportingPolicy shared core with span/run ContextVars for nested, thread/async-local isolation
• ReportEvent model plus NoOp/InMemory/Logging/Composite/UI reporters and a bounded UI polling buffer
• Tracing/metrics/alerts policies and OpenTelemetry tracing/metrics integration (exposed via otel/full/develop/test extras)
• Structural reporting models and a Reporting{Evaluator,Model} taxonomy with placeholder vendor classes
• Refactor LoggingEvaluator onto LoggingPolicy to share formatting and enable LoggingModel while preserving the existing import path and log output
• Retry lifecycle events now carry run_id and child depth via current_span_depth(); reporter failures are isolated on reporting/retry paths
• DryRunEvaluator with context-local planning guard; synthetic mode is non-transparent so results are not cached under real-run keys; node_key strips the dry-run evaluator layer while preserving non-evaluator options so it matches cache_key() for the logical node
• ReportingStateStore preserves terminal outcomes while allowing retry streams to progress
• Docs: reporting workflow, reporter options, OpenTelemetry install, reserved run/graph phases, extra payload keys, and dry-run synthetic-result warnings
• Tests across utils/evaluators/models covering success/error flows, dry-run override recursion, cache composition, concurrent dry-run reuse, node-key semantics, retry event nesting, reporter failure isolation, and state folding

[github-actions]

Test Results

  1 files  ± 0    1 suites  ±0   2m 38s ⏱️ -1s
962 tests +83  960 ✅ +83  2 💤 ±0  0 ❌ ±0 
968 runs  +83  966 ✅ +83  2 💤 ±0  0 ❌ ±0 

Results for commit fe2c974. ± Comparison against base commit 0662c2a.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

❌ Patch coverage is 96.73540% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.40%. Comparing base (0662c2a) to head (fe2c974).

Files with missing lines	Patch %	Lines
ccflow/utils/reporting.py	93.57%	17 Missing and 8 partials ⚠️
ccflow/evaluators/reporting.py	91.46%	5 Missing and 2 partials ⚠️
ccflow/tests/evaluators/test_reporting.py	98.07%	4 Missing ⚠️
ccflow/tests/models/test_reporting.py	97.01%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #231      +/-   ##
==========================================
+ Coverage   94.19%   94.40%   +0.21%     
==========================================
  Files         150      156       +6     
  Lines       12094    13196    +1102     
  Branches      665      706      +41     
==========================================
+ Hits        11392    12458    +1066     
- Misses        570      596      +26     
- Partials      132      142      +10     

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