docs: add implementation plan, ADRs, and task tracking system

- Add comprehensive 8-phase implementation plan (docs/plan.md)
- Add 28 Architecture Decision Records (docs/adr/) covering all phases
- Add task tracking system with 283+ task files (docs/stories/)
- Add task generator script for automated task file creation
- Add reference playbooks and requirements documentation

This commit establishes the complete planning foundation for the Go
Platform implementation, documenting all architectural decisions and
providing detailed task breakdown for Phases 0-8.

docs/adr/0021-module-loading-strategy.md

@@ -0,0 +1,54 @@
+# ADR-0021: Module Loading Strategy
+
+## Status
+Accepted
+
+## Context
+The platform needs to support pluggable modules. Two approaches:
+1. **Static registration** - Modules compiled into binary
+2. **Dynamic plugin loading** - Load `.so` files at runtime
+
+Each has trade-offs for development, CI, and production.
+
+## Decision
+Support **both approaches** with **static registration as primary**:
+
+1. **Static registration (primary)**:
+   - Modules register via `init()` function
+   - Imported via `import _ "module/pkg"` in main
+   - Works everywhere (Windows, Linux, macOS)
+   - Compile-time type safety
+
+2. **Dynamic plugin loading (optional)**:
+   - Support via Go `plugin` package
+   - Load `.so` files from `./plugins/` directory
+   - Only for production scenarios requiring hot-swap
+   - Linux/macOS only (Go plugin limitation)
+
+**Rationale:**
+- Static registration is simpler and more reliable
+- Works in CI/CD (no plugin compilation needed)
+- Compile-time safety catches errors early
+- Dynamic loading provides flexibility for specific use cases
+- Modules can choose their approach
+
+## Consequences
+
+### Positive
+- Flexible: static for most cases, dynamic when needed
+- Static registration works everywhere
+- Compile-time safety with static
+- Hot-swap capability with dynamic (Linux/macOS)
+
+### Negative
+- Two code paths to maintain
+- Dynamic plugins have version compatibility constraints
+- Plugin debugging is harder
+
+### Implementation Notes
+- Implement static registry in `internal/registry/registry.go`
+- Modules register via: `registry.Register(Module)` in `init()`
+- Implement plugin loader in `internal/pluginloader/plugin_loader.go` (optional)
+- Document when to use each approach
+- Validate plugin version compatibility if using dynamic loading
+