feat(agents): p50-lateness tolerance + per-project realness for overdue-task (#115)

Replaces snooze-rate heuristic with p50 of actual task lateness (completedAt − dueAt).
Adds project_realness inference: projects with chronic lateness get realness < 1 and
the agent softens its snippet language from "overdue" to "past target date".

- TaskCompletion added to UserHistory with lateness_days computed property
- _infer_lateness_tolerance: p50 of task_completions, clipped at 0, float
- _infer_project_realness: per-project median lateness normalised by global median
- Both InferredParams use 7d TTL; cold_start = 0.0 / {}
- AgentInferRequest accepts task_completions; endpoint wires them through
- 12 new tests covering punctual/chronic/mixed users and language softening
- Agent bumped to v1.2.0

Closes #115

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

ml/serving/main.py

@@ -40,7 +40,7 @@ if _repo_root not in sys.path:
 
 from ml.agents.base import AgentInput  # noqa: E402
 from ml.agents.registry import get_agent, all_agents, all_manifests, get_manifest  # noqa: E402
-from ml.agents.inference import run_inference, FeedbackEvent, UserHistory  # noqa: E402
+from ml.agents.inference import run_inference, FeedbackEvent, TaskCompletion, UserHistory  # noqa: E402
 
 logging_config.configure()
 
@@ -141,7 +141,8 @@ class AgentComputeResponse(BaseModel):
 
 class AgentInferRequest(BaseModel):
     user_id: str
-    feedback_history: list[dict] = []   # [{action, dwell_ms, created_at}, …]
+    feedback_history: list[dict] = []        # [{action, dwell_ms, created_at}, …]
+    task_completions: list[dict] = []        # [{project_id, completed_at, due_at}, …]
 
 
 class AgentInferResponse(BaseModel):
@@ -284,7 +285,15 @@ async def infer_agent(agent_id: str, req: AgentInferRequest) -> AgentInferRespon
         )
         for e in req.feedback_history
     ]
-    history = UserHistory(user_id=req.user_id, events=events)
+    completions = [
+        TaskCompletion(
+            project_id=c.get("project_id"),
+            completed_at=c.get("completed_at", ""),
+            due_at=c.get("due_at", ""),
+        )
+        for c in req.task_completions
+    ]
+    history = UserHistory(user_id=req.user_id, events=events, task_completions=completions)
 
     t0 = __import__("time").monotonic()
     inferred = run_inference(manifest, history)