feat: package as Claude Code plugin with marketplace distribution

- Add .claude-plugin/plugin.json manifest for direct installation
- Add .claude-plugin/marketplace.json for marketplace distribution
- Reorganize skills to proper skill-name/SKILL.md format
- Update hooks.json with relative paths for portability
- Add new skills: continuous-learning, strategic-compact, eval-harness, verification-loop
- Add new commands: checkpoint, eval, orchestrate, verify
- Update README with plugin installation instructions

Install via:
  /plugin marketplace add affaan-m/everything-claude-code
  /plugin install everything-claude-code@everything-claude-code

commands/checkpoint.md

@@ -0,0 +1,74 @@
+# Checkpoint Command
+
+Create or verify a checkpoint in your workflow.
+
+## Usage
+
+`/checkpoint [create|verify|list] [name]`
+
+## Create Checkpoint
+
+When creating a checkpoint:
+
+1. Run `/verify quick` to ensure current state is clean
+2. Create a git stash or commit with checkpoint name
+3. Log checkpoint to `.claude/checkpoints.log`:
+
+```bash
+echo "$(date +%Y-%m-%d-%H:%M) | $CHECKPOINT_NAME | $(git rev-parse --short HEAD)" >> .claude/checkpoints.log
+```
+
+4. Report checkpoint created
+
+## Verify Checkpoint
+
+When verifying against a checkpoint:
+
+1. Read checkpoint from log
+2. Compare current state to checkpoint:
+   - Files added since checkpoint
+   - Files modified since checkpoint
+   - Test pass rate now vs then
+   - Coverage now vs then
+
+3. Report:
+```
+CHECKPOINT COMPARISON: $NAME
+============================
+Files changed: X
+Tests: +Y passed / -Z failed
+Coverage: +X% / -Y%
+Build: [PASS/FAIL]
+```
+
+## List Checkpoints
+
+Show all checkpoints with:
+- Name
+- Timestamp
+- Git SHA
+- Status (current, behind, ahead)
+
+## Workflow
+
+Typical checkpoint flow:
+
+```
+[Start] --> /checkpoint create "feature-start"
+   |
+[Implement] --> /checkpoint create "core-done"
+   |
+[Test] --> /checkpoint verify "core-done"
+   |
+[Refactor] --> /checkpoint create "refactor-done"
+   |
+[PR] --> /checkpoint verify "feature-start"
+```
+
+## Arguments
+
+$ARGUMENTS:
+- `create <name>` - Create named checkpoint
+- `verify <name>` - Verify against named checkpoint
+- `list` - Show all checkpoints
+- `clear` - Remove old checkpoints (keeps last 5)