feat(skill): ck — context-keeper v2, persistent per-project memory

Adds the ck (Context Keeper) skill — deterministic Node.js scripts
that give Claude Code persistent, per-project memory across sessions.

Architecture:
- commands/ — 8 Node.js scripts handle all command logic (init, save,
  resume, info, list, forget, migrate, shared). Claude calls scripts
  and displays output — no LLM interpretation of command logic.
- hooks/session-start.mjs — injects ~100 token compact summary on
  session start (not kilobytes). Detects unsaved sessions, git
  activity since last save, goal mismatch vs CLAUDE.md.
- context.json as source of truth — CONTEXT.md is generated from it.
  Full session history, session IDs, git activity per save.

Commands: /ck:init /ck:save /ck:resume /ck:info /ck:list /ck:forget /ck:migrate
Source: https://github.com/sreedhargs89/context-keeper
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

skills/ck/commands/forget.mjs

@@ -0,0 +1,44 @@
+#!/usr/bin/env node
+/**
+ * ck — Context Keeper v2
+ * forget.mjs — remove a project's context and registry entry
+ *
+ * Usage: node forget.mjs [name|number]
+ * stdout: confirmation or error
+ * exit 0: success  exit 1: not found
+ *
+ * Note: SKILL.md instructs Claude to ask "Are you sure?" before calling this script.
+ * This script is the "do it" step — no confirmation prompt here.
+ */
+
+import { rmSync } from 'fs';
+import { resolve } from 'path';
+import { resolveContext, readProjects, writeProjects, CONTEXTS_DIR } from './shared.mjs';
+
+const arg = process.argv[2];
+const cwd = process.env.PWD || process.cwd();
+
+const resolved = resolveContext(arg, cwd);
+if (!resolved) {
+  const hint = arg ? `No project matching "${arg}".` : 'This directory is not registered.';
+  console.log(`${hint}`);
+  process.exit(1);
+}
+
+const { name, contextDir, projectPath } = resolved;
+
+// Remove context directory
+const contextDirPath = resolve(CONTEXTS_DIR, contextDir);
+try {
+  rmSync(contextDirPath, { recursive: true, force: true });
+} catch (e) {
+  console.log(`ck: could not remove context directory — ${e.message}`);
+  process.exit(1);
+}
+
+// Remove from projects.json
+const projects = readProjects();
+delete projects[projectPath];
+writeProjects(projects);
+
+console.log(`✓ Context for '${name}' removed.`);