feat(agents): add plan + review agent skills

.agents/skills/plan/SKILL.md

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+---
+name: plan
+description: OPT-IN file-based planning for multi-session tasks. Only use when user explicitly requests it or work spans multiple sessions. For single-session work, prefer your platform's native planning features.
+disable-model-invocation: true
+---
+
+# File-Based Task Plan Template
+
+## Default: Use Your Platform's Native Planning
+
+**For single-session work, prefer your AI platform's built-in planning features.**
+This file-based approach adds overhead that's only justified for specific scenarios.
+
+## When to Use THIS Skill (Opt-In)
+
+Only use this file-based plan template when:
+- **User explicitly requests it** ("use the plan template", "create a plan file")
+- **Work spans multiple sessions** and must survive context resets
+- **Handoff to another AI/human** who needs full written context
+- **Complex multi-PR coordination** requiring persistent state
+
+## Setup
+
+1. Copy this template to `plans/[task_name]/plan.md` (`plans/` is gitignored — local working memory, never committed)
+2. Replace all `[placeholders]` with actual values
+3. Fill out Context sections completely
+4. Start with Step 1 marked as IN_PROGRESS
+
+## Critical Meta-Goals
+
+**THIS PLAN MUST BE:**
+1. **FULLY SELF-DESCRIBING**: All context needed to resume work is IN THIS FILE
+2. **CONSTANTLY UPDATED**: Every action's results recorded IMMEDIATELY in the step
+3. **THE SINGLE SOURCE OF TRUTH**: If it's not in the plan, it didn't happen
+4. **SAFE TO RESUME**: Any AI can pick up work by reading ONLY this file
+
+**REMEMBER**: External memory is unreliable. This plan is your ONLY memory.
+
+## Anti-Drift Protocol
+
+### The Three Commandments
+1. **RELOAD BEFORE EVERY ACTION**: Your memory has been wiped. This plan is all you have.
+2. **UPDATE AFTER EVERY ACTION**: If you don't write it down, it never happened.
+3. **TRUST ONLY THE PLAN**: Not your memory, not your assumptions, ONLY what's written here.
+
+### Critical Rules
+- **ONE TASK AT A TIME** - Never jump ahead
+- **NO ASSUMPTIONS** - The plan is the only truth
+- **NO OFFROADING** - If it's not in the plan, don't do it
+
+### Step Execution Protocol
+**BEFORE EVERY SINGLE ACTION:**
+1. **RELOAD PLAN**: `cat plans/[task_name]/plan.md | head -200`
+2. **FIND YOUR TASK**: Locate the current IN_PROGRESS step
+3. **EXECUTE**: ONLY do what that step says
+4. **UPDATE IMMEDIATELY**: Edit this plan with results BEFORE doing anything else. Also scan future TODO steps; if any will need outputs from this step, inline them as `**from_step <this-step-id>**: <fact>` (see Forward-Propagating Outputs below).
+5. **VERIFY**: `tail -50 plans/[task_name]/plan.md`
+
+### Forward-Propagating Outputs
+
+When closing a step, if a future TODO step will consume a fact you just produced, inline it there now with a `**from_step <id>**: <fact> (<how to re-verify>)` line. Saves the re-lookup and avoids relying on memory. Only do this for facts the future step actually needs; if the value looks stale when that step starts, re-verify and update the line in place.
+
+### If Confused
+1. STOP
+2. Reload this plan
+3. Find the last completed step
+4. Continue from there
+
+## Plan Template
+
+```markdown
+# [Task Name] Plan
+**THIS PLAN FILE**: `plans/[task_name]/plan.md`
+**Created**: [DATE TIME TIMEZONE]
+**Current Branch**: [from `git branch --show-current`]
+**PRs**: [PR number + title + plan role]
+**PR Target Branch**: [where this will merge]
+**Base branch**: [FILL ME IN, TYPICALLY PR TARGET BRANCH]
+
+## Context (READ-ONLY)
+
+### Plan Overview
+**Raw Prompt**: [What the user said, verbatim]
+**Goal**: [What we're trying to achieve]
+**Description**: [Brief description of the task]
+**Success Criteria**: [How we know we're done]
+**Key Constraints**: [Important limitations or requirements]
+
+### Technical Context
+**Initial State**:
+- Working Directory: [pwd output]
+- Current Branch: `[branch-name]` (forked from `[parent]` at `[SHA]`)
+- Target Branch: `[where this merges to]`
+
+### Strategy
+**Approach**: [High-level plan]
+**Key Decisions**:
+- [Decision 1]: [Reasoning]
+- [Decision 2]: [Reasoning]
+
+## Quick Reference
+```bash
+# Reload plan
+cat plans/[task_name]/plan.md | head -200
+
+# Local validation before pushing (Python: flake8 + pytest, per DEVELOP.md)
+(cd src/python && ./bin/lint.sh && python3 -m pytest test)
+
+# Docker build smoke (slow; mirrors CI test-docker)
+(cd src/docker && ./dc.cpu build)
+
+# CI monitoring (bounded polling, not --watch streams)
+gh pr checks [PR]
+```
+
+## Status Legend
+- TODO: Not started
+- IN_PROGRESS: Currently working on this
+- DONE: Completed successfully
+- FAILED: Failed, needs retry
+- SKIPPED: Not needed
+- BLOCKED: Can't proceed
+
+## LIVE PLAN
+
+### Steps
+
+#### Step 1: [Description]
+**Status**: IN_PROGRESS
+**Action**: [What to do]
+**Success Criteria**: [How to verify]
+**Result**:
+```
+[Fill in with commands, output, decisions, errors]
+```
+
+#### Step 2: [Description]
+**Status**: TODO
+**Action**: [What to do]
+**Success Criteria**: [How to verify]
+```
+
+## Step Compaction
+
+**Every ~30 completed steps, compact the plan:**
+1. Create history file: `plans/[task_name]/history/steps<start>-to-<end>.md`
+2. Replace archived steps with summary in plan
+3. Continue with next step number