Fix Windows bulk test + dual MCP config location + CONTRIBUTING.md

- Bulk test: use cbm_tmpdir() instead of hardcoded /tmp/ (fixes
  Windows/MSYS2 where /tmp/ doesn't resolve for SQLite)
- Install: write MCP config to both ~/.claude/.mcp.json (Claude Code
  <=2.1.x) and ~/.claude.json (Claude Code >=2.1.80). Fixes #69.
- Uninstall: remove from both locations
- CONTRIBUTING.md: rewrite for pure C project (was still describing Go,
  causing contributors to submit Go PRs)
- Fix clang-format in mcp.c protocol version negotiation (PR #79 merge)

Author: DeusData

src/cli/cli.c

@@ -2188,14 +2188,23 @@ int cbm_cmd_install(int argc, char **argv) {
             printf("  removed old monolithic skill\n");
         }
 
-        /* MCP config (.mcp.json) */
+        /* MCP config — write to both locations for compatibility.
+         * Claude Code <=2.1.x reads ~/.claude/.mcp.json
+         * Claude Code >=2.1.80 reads ~/.claude.json */
         char mcp_path[1024];
         snprintf(mcp_path, sizeof(mcp_path), "%s/.claude/.mcp.json", home);
         if (!dry_run) {
             cbm_install_editor_mcp(self_path, mcp_path);
         }
         printf("  mcp: %s\n", mcp_path);
 
+        char mcp_path2[1024];
+        snprintf(mcp_path2, sizeof(mcp_path2), "%s/.claude.json", home);
+        if (!dry_run) {
+            cbm_install_editor_mcp(self_path, mcp_path2);
+        }
+        printf("  mcp: %s\n", mcp_path2);
+
         /* PreToolUse hook */
         char settings_path[1024];
         snprintf(settings_path, sizeof(settings_path), "%s/.claude/settings.json", home);
@@ -2403,6 +2412,13 @@ int cbm_cmd_uninstall(int argc, char **argv) {
         }
         printf("  removed MCP config entry\n");
 
+        /* Also remove from new location (Claude Code >=2.1.80) */
+        char mcp_path2[1024];
+        snprintf(mcp_path2, sizeof(mcp_path2), "%s/.claude.json", home);
+        if (!dry_run) {
+            cbm_remove_editor_mcp(mcp_path2);
+        }
+
         char settings_path[1024];
         snprintf(settings_path, sizeof(settings_path), "%s/.claude/settings.json", home);
         if (!dry_run) {

tests/test_store_bulk.c

@@ -14,6 +14,7 @@
  */
 #include "test_framework.h"
 #include <store/store.h>
+#include <foundation/compat.h>
 #include <sqlite3.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -43,7 +44,7 @@ static char *get_journal_mode(const char *db_path) {
 }
 
 static void make_temp_path(char *buf, size_t n) {
-    snprintf(buf, n, "/tmp/cmm_bulk_test_%d.db", (int)getpid());
+    snprintf(buf, n, "%s/cmm_bulk_test_%d.db", cbm_tmpdir(), (int)getpid());
 }
 
 static void cleanup_db(const char *path) {