feat: complete OpenCode plugin support with hooks, tools, and commands

Major OpenCode integration overhaul:

- llms.txt: Comprehensive OpenCode documentation for LLMs (642 lines)
- .opencode/plugins/ecc-hooks.ts: All Claude Code hooks translated to OpenCode's plugin system
- .opencode/tools/*.ts: 3 custom tools (run-tests, check-coverage, security-audit)
- .opencode/commands/*.md: All 24 commands in OpenCode format
- .opencode/package.json: npm package structure for opencode-ecc
- .opencode/index.ts: Main plugin entry point

- Delete incorrect LIMITATIONS.md (hooks ARE supported via plugins)
- Rewrite MIGRATION.md with correct hook event mapping
- Update README.md OpenCode section to show full feature parity

OpenCode has 20+ events vs Claude Code's 3 phases:
- PreToolUse → tool.execute.before
- PostToolUse → tool.execute.after
- Stop → session.idle
- SessionStart → session.created
- SessionEnd → session.deleted
- Plus: file.edited, file.watcher.updated, permission.asked, todo.updated

- 12 agents: Full parity
- 24 commands: Full parity (+1 from original 23)
- 16 skills: Full parity
- Hooks: OpenCode has MORE (20+ events vs 3 phases)
- Custom Tools: 3 native OpenCode tools

The OpenCode configuration can now be:
1. Used directly: cd everything-claude-code && opencode
2. Installed via npm: npm install opencode-ecc

.opencode/commands/eval.md

@@ -0,0 +1,88 @@
+---
+description: Run evaluation against acceptance criteria
+agent: build
+---
+
+# Eval Command
+
+Evaluate implementation against acceptance criteria: $ARGUMENTS
+
+## Your Task
+
+Run structured evaluation to verify the implementation meets requirements.
+
+## Evaluation Framework
+
+### Grader Types
+
+1. **Binary Grader** - Pass/Fail
+   - Does it work? Yes/No
+   - Good for: feature completion, bug fixes
+
+2. **Scalar Grader** - Score 0-100
+   - How well does it work?
+   - Good for: performance, quality metrics
+
+3. **Rubric Grader** - Category scores
+   - Multiple dimensions evaluated
+   - Good for: comprehensive review
+
+## Evaluation Process
+
+### Step 1: Define Criteria
+
+```
+Acceptance Criteria:
+1. [Criterion 1] - [weight]
+2. [Criterion 2] - [weight]
+3. [Criterion 3] - [weight]
+```
+
+### Step 2: Run Tests
+
+For each criterion:
+- Execute relevant test
+- Collect evidence
+- Score result
+
+### Step 3: Calculate Score
+
+```
+Final Score = Σ (criterion_score × weight) / total_weight
+```
+
+### Step 4: Report
+
+## Evaluation Report
+
+### Overall: [PASS/FAIL] (Score: X/100)
+
+### Criterion Breakdown
+
+| Criterion | Score | Weight | Weighted |
+|-----------|-------|--------|----------|
+| [Criterion 1] | X/10 | 30% | X |
+| [Criterion 2] | X/10 | 40% | X |
+| [Criterion 3] | X/10 | 30% | X |
+
+### Evidence
+
+**Criterion 1: [Name]**
+- Test: [what was tested]
+- Result: [outcome]
+- Evidence: [screenshot, log, output]
+
+### Recommendations
+
+[If not passing, what needs to change]
+
+## Pass@K Metrics
+
+For non-deterministic evaluations:
+- Run K times
+- Calculate pass rate
+- Report: "Pass@K = X/K"
+
+---
+
+**TIP**: Use eval for acceptance testing before marking features complete.