docs: add [Unreleased] CHANGELOG entries for post-v3.8.0 work

Document recent merged work in the [Unreleased] section:

Added:
- Comprehensive Worker Tracking System (all 16 supervisors with OpenCode API monitoring)
- Centralized Automation Tracking Manager subagent (prevents cycle reuse issues)
- Plan Action Argument Upsert fix (#4174)

Changed:
- Product-Builder Tracking Migration to individual per-cycle tracking issues
- Implementation Orchestrator Scaling to 32 parallel workers

Fixed:
- ACMS Indexing Pipeline CLI Wiring: ContextTierService was empty on CLI invocations, causing LLM to receive zero file context during plan execution (#1028)
- CI Lint: 51 ruff violations in scripts/validate_automation_tracking.py
- CI Integration Tests: stale tdd_expected_fail tag in coverage_threshold.robot removed (#5266)
- Orchestrator Worker Dispatch: verify_worker_started() API response format fix

Also moves the ACMS fix from the incorrect Changed section to the correct Fixed section.

Plus align the A2A ASV benchmark suite with the JSON-RPC 2.0 method rename so CI stays green.

ISSUES CLOSED: #6852

benchmarks/a2a_facade_bench.py

@@ -76,12 +76,13 @@ class VersionNegotiationSuite:
 
     def setup(self) -> None:
         self.negotiator = A2aVersionNegotiator()
+        self.current_version = self.negotiator.get_current()
 
     def time_negotiate_supported(self) -> None:
-        self.negotiator.negotiate("1.0")
+        self.negotiator.negotiate(self.current_version)
 
     def time_is_supported_true(self) -> None:
-        self.negotiator.is_supported("1.0")
+        self.negotiator.is_supported(self.current_version)
 
     def time_is_supported_false(self) -> None:
         self.negotiator.is_supported("99.0")