session-memory: Claude + Codex + Grok distributors + registry (WP-0007 T02/T03)

Thin per-flavor distributors over the shared base: Claude (CLAUDE.md, optional
skill-stub mode), Codex (AGENTS.md), Grok (.grok/instructions.md). registry maps
flavor->distributor — adding a flavor is one entry + one module. Same agnostic
body renders to distinct per-flavor targets (FR-A3). 7 new tests; suite 117/117.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

session_memory/distribute/registry.py

@@ -0,0 +1,26 @@
+"""Distributor registry (T03) — flavor -> distributor, the one place that knows
+about all flavor edges. Adding a flavor = one entry here + one adapter module.
+"""
+
+from __future__ import annotations
+
+from typing import Optional
+
+from .base import BaseDistributor
+from .claude import ClaudeDistributor
+from .codex import CodexDistributor
+from .grok import GrokDistributor
+
+_REGISTRY: dict[str, BaseDistributor] = {
+    "claude": ClaudeDistributor(),
+    "codex": CodexDistributor(),
+    "grok": GrokDistributor(),
+}
+
+
+def get_distributor(flavor: str) -> Optional[BaseDistributor]:
+    return _REGISTRY.get(flavor)
+
+
+def all_flavors() -> list[str]:
+    return list(_REGISTRY)