feat(qg0): configurable QG-0 title limit via ORCH_QG0_TITLE_MAX (default 200)

Replace the hardcoded `len(name) > 80` cap in the QG-0 entry validation
(_qg0_errors) with a configurable Settings.qg0_title_max (env
ORCH_QG0_TITLE_MAX, default 200). The 80-char cap was a hygiene limit, not
structural, so valid 81-200 char titles were rejected without a business
reason. The limit is read dynamically per call and the error text interpolates
the active value.

Graceful degradation (AC-3, self-hosting safety): an empty/non-numeric env
value no longer crashes the process on startup. A field_validator(mode="before")
intercepts the raw env before int-parsing and falls back to 200 (never raises),
suppressing pydantic ValidationError.

Additive and backward-compatible (default 200 > old 80). Invariants unchanged:
STAGE_TRANSITIONS, QG_CHECKS registry, DB schema, slug [:30], lower limits,
soft-QG-0 warning path, API.

Refs: ORCH-069

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/config.py

@@ -1,3 +1,4 @@
+from pydantic import field_validator
 from pydantic_settings import BaseSettings
 
 
@@ -407,6 +408,24 @@ class Settings(BaseSettings):
     # Неизвестное/пустое значение трактуется как edit (см. notifications).
     tracker_mode: str = "edit"
 
+    # ORCH-069: QG-0 upper title-length limit (entry gate _qg0_errors). The 80-char
+    # cap was a hygiene limit, not structural (slug is cut to [:30] independently,
+    # DB title TEXT is unbounded). Configurable via env ORCH_QG0_TITLE_MAX; default
+    # 200 (was hardcoded 80). Invalid/empty value -> default (graceful, no crash).
+    qg0_title_max: int = 200
+
+    @field_validator("qg0_title_max", mode="before")
+    @classmethod
+    def _qg0_title_max_default(cls, v):
+        # Graceful (ORCH-069 AC-3): empty / non-numeric env -> default 200, the
+        # process must not crash on startup. Never raises (self-hosting safety).
+        try:
+            if v is None or (isinstance(v, str) and v.strip() == ""):
+                return 200
+            return int(v)
+        except (TypeError, ValueError):
+            return 200
+
     class Config:
         env_prefix = "ORCH_"
         env_file = ".env"