[AZ-273] [AZ-274] [AZ-275] [AZ-267] [AZ-268] FDR producer chain + log bridge + contract test

AZ-273: lock-free SPSC ring buffer with pre-allocated slots, power-of-
two capacity, opt-in SPSC guard, and EnqueueResult / FdrSpscViolationError
on the public surface. make_fdr_client caches one client per producer_id
and reads capacity from config.fdr.per_producer_capacity with fallback
to queue_size.
AZ-274: default_overrun_policy implements drop-oldest + retry + immediate
marker emission, with prior-marker dropped_count folding via _evict_one
so user-loss info is never lost across iterations. ERROR diagnostic is
rate-limited to <=1/sec per producer.
AZ-275: FakeFdrSink mirrors the FdrClient public surface and reuses the
production default_overrun_policy via a duck-typed _PolicyAdapter. The
test-only records/all_records_ever properties let component tests assert
both in-buffer and lifetime state. tests/conftest.py registers the
fake_fdr_sink fixture and an AST architecture lint forbids production
imports of fakes.
AZ-267: FdrLogBridgeHandler installs on the root logger via wire_log_bridge
and forwards only WARN+ERROR records into the FDR with kind="log".
Thread-local recursion guard short-circuits internal logging; saturated-
queue diagnostics go to stderr every N=1000 drops.
AZ-268: tests/contract/log_schema.py covers every row of the schema's
Test Cases table plus the "DEBUG+INFO never reach FDR" invariant.
pyproject.toml registers the contract pytest marker and the
contract-mandated log_schema.py file-name.
251 unit + contract tests pass (48 new). Review verdict:
PASS_WITH_WARNINGS; findings are NFR-perf deferrals + documented
relaxation of AZ-274 AC-2 coalescing under permanently-stalled consumer.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/gps_denied_onboard/config/schema.py

@@ -50,13 +50,16 @@ class LogConfig:
 class FdrConfig:
     """Cross-cutting Flight Data Recorder block (E-CC-FDR-CLIENT / AZ-247).
 
-    The producer-side ring-buffer fields below are documented defaults
-    consumed by AZ-273; only the outer container is owned by AZ-269.
+    ``queue_size`` is the documented default capacity for every producer.
+    ``per_producer_capacity`` carries per-producer overrides keyed by
+    producer slug (consumed by AZ-273 ``make_fdr_client``); blocks
+    that omit a producer fall back to ``queue_size``.
     """
 
     queue_size: int = 4096
     overrun_policy: str = "drop_oldest"
     path: str = "/var/lib/gps-denied/fdr"
+    per_producer_capacity: Mapping[str, int] = field(default_factory=dict)
 
 
 @dataclass(frozen=True)