rename .story_kit directory to .storkit and update all references

Renames the config directory and updates 514 references across 42 Rust
source files, plus CLAUDE.md, .gitignore, Makefile, script/release,
and .mcp.json files. All 1205 tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.storkit/.gitignore

@@ -0,0 +1,22 @@
+# Bot config (contains credentials)
+bot.toml
+
+# Matrix SDK state store
+matrix_store/
+matrix_device_id
+matrix_history.json
+
+# Agent worktrees and merge workspace (managed by the server, not tracked in git)
+worktrees/
+merge_workspace/
+
+# Intermediate pipeline stages (transient, not committed per spike 92)
+work/2_current/
+work/3_qa/
+work/4_merge/
+
+# Coverage reports (generated by cargo-llvm-cov, not tracked in git)
+coverage/
+
+# Token usage log (generated at runtime, contains cost data)
+token_usage.jsonl