[Bug] Unnecessary plugin documentation auto-loaded at session start consuming 35% context window

Bug Description
Title:
Context window bloat: 35% consumed by auto-loaded plugin docs on session start

Description:
## Issue
Session context is being bloated with unnecessary plugin documentation and skill
listings at startup (consuming ~35% of context window), despite plugins being
pre-installed and not actively used in this session.

## What's being loaded

• superpowers:using-superpowers skill (massive introduction + flow diagram)
• Complete enumeration of 100+ available skills (skills list)
• Vercel platform knowledge dump (even on non-Vercel projects)
• MCP server instructions
• Multiple system reminders with lengthy examples

## Expected behavior
Plugin documentation should load on-demand (when /skill is invoked or skill is
referenced), not auto-injected at every session start.

## Current behavior
All plugin context is pre-loaded regardless of whether the session will use those
plugins.

## Environment

• Claude Code version: (check with claude --version)
• Platform: macOS
• Plugins enabled: 20 (superpowers, vercel, medusa-dev, expo, etc.)
• Model: haiku

## Steps to reproduce

1. Start a new Claude Code session
2. Check context usage immediately
3. Observe ~35% is consumed by plugin docs not used in current session

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.110
• Feedback ID: cfb508c9-2a8d-4667-905a-e0690d9eedad

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/keerthi/.local/share/claude/versions/2.1.110 (expected in multi-process scenarios)\n    at kU_ (/$bunfs/root/src/entrypoints/cli.js:2751:2153)\n    at Mt6 (/$bunfs/root/src/entrypoints/cli.js:2751:1233)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-16T13:25:32.859Z"},{"error":"Error: Plugin path not found: /Users/keerthi/.claude/plugins/marketplaces/claude-plugins-official/external_plugins/autofix-bot\n    at P91 (/$bunfs/root/src/entrypoints/cli.js:1035:10941)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:1035:9256)\n    at async Jz9 (/$bunfs/root/src/entrypoints/cli.js:1035:8470)\n    at async Wz9 (/$bunfs/root/src/entrypoints/cli.js:1035:20463)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:1035:21911)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:8364:6468)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-16T13:25:33.443Z"},{"error":"Error: Failed to clone repository for git-subdir source: Cloning into '/Users/keerthi/.claude/plugins/cache/temp_subdir_1776345933448_p17a0l.clone'...\ngit@github.com: Permission denied (publickey).\r\nfatal: Could not read from remote repository.\n\nPlease make sure you have the correct access rights\nand the repository exists.\n    at w91 (/$bunfs/root/src/entrypoints/cli.js:1029:54012)\n    at async NtH (/$bunfs/root/src/entrypoints/cli.js:1029:56341)\n    at async P91 (/$bunfs/root/src/entrypoints/cli.js:1035:11949)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:1035:9256)\n    at async Jz9 (/$bunfs/root/src/entrypoints/cli.js:1035:8470)\n    at async Wz9 (/$bunfs/root/src/entrypoints/cli.js:1035:20463)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:1035:21911)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:8364:6468)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-16T13:25:34.403Z"},{"error":"Error: Failed to clone repository for git-subdir source: Cloning into '/Users/keerthi/.claude/plugins/cache/temp_subdir_1776345933444_org2qd.clone'...\ngit@github.com: Permission denied (publickey).\r\nfatal: Could not read from remote repository.\n\nPlease make sure you have the correct access rights\nand the repository exists.\n    at w91 (/$bunfs/root/src/entrypoints/cli.js:1029:54012)\n    at async NtH (/$bunfs/root/src/entrypoints/cli.js:1029:56341)\n    at async P91 (/$bunfs/root/src/entrypoints/cli.js:1035:11949)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:1035:9256)\n    at async Jz9 (/$bunfs/root/src/entrypoints/cli.js:1035:8470)\n    at async Wz9 (/$bunfs/root/src/entrypoints/cli.js:1035:20463)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:1035:21911)\n    at async <anonymous> (/$bunfs/root/src/entrypoints/cli.js:8364:6468)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-16T13:25:34.403Z"},{"error":"Error: File does not exist. Note: your current working directory is /Users/keerthi/Downloads/dev/clipd_review.\n    at call (/$bunfs/root/src/entrypoints/cli.js:4732:7630)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-16T13:31:38.294Z"}]