patcher: pin model='opus' on clawdforge sessions; CRAFTING_PATCHER_MODEL env override

Code-work prompts (read CVE/lint context, draft a unified diff that
verifies cleanly against the failing recipe) reward Opus's longer
context + careful reasoning. Cauldron-style high-frequency Sonnet calls
are unaffected — this only changes what crafting-table's patcher asks
clawdforge to use for its drafted-patch sessions.

Pairs with clawdforge dbbead2 which adds the optional `model` field on
POST /sessions and propagates ANTHROPIC_MODEL into the acpx subprocess
env on both create + turn.

Override knob: CRAFTING_PATCHER_MODEL env (e.g. "sonnet" if cost > quality).

Tests: 16/16 patcher tests still green.

crafting_table/patcher.py

@@ -98,6 +98,12 @@ class PatcherConfig:
     # HTTP timeout margin — clawdforge adds an internal margin, but we cap
     # transport-level too for hung connections.
     http_timeout_secs: int = 600
+    # Model passed to clawdforge on session create. Pinned to "opus" by
+    # default — code-work prompts (read finding context, write a unified
+    # diff that doesn't break the verify recipe) reward Opus's longer
+    # context + deeper reasoning. Override via CRAFTING_PATCHER_MODEL env
+    # if you want sonnet for cost reasons.
+    model: str = "opus"
 
     @classmethod
     def from_env(cls, env: dict[str, str] | None = None) -> "PatcherConfig | None":
@@ -127,6 +133,7 @@ class PatcherConfig:
             auto_patch_branch_prefix=e.get(
                 "CRAFTING_PATCHER_BRANCH_PREFIX", "crafting-table/auto/"
             ),
+            model=e.get("CRAFTING_PATCHER_MODEL", "opus"),
         )
 
 
@@ -210,9 +217,12 @@ class ClawdforgeClient:
         self,
         *,
         agent: str = "claude",
+        model: str | None = None,
         meta: dict[str, Any] | None = None,
     ) -> dict[str, Any]:
         body: dict[str, Any] = {"agent": agent}
+        if model is not None:
+            body["model"] = model
         if meta is not None:
             body["meta"] = meta
         async with httpx.AsyncClient(timeout=self.timeout_secs) as ac:
@@ -657,6 +667,7 @@ class Patcher:
         try:
             session_payload = await self.clawdforge.create_session(
                 agent="claude",
+                model=self.config.model,
                 meta={
                     "crafting_table_job_id": job["id"],
                     "finding_id": finding_id,