add Plano agent skills framework and rule set (#797)

* feat: add initial documentation for Plano Agent Skills

* feat: readme with examples

* feat: add detailed skills documentation and examples for Plano

---------

Co-authored-by: Adil Hafeez <adil.hafeez@gmail.com>

skills/rules/routing-aliases.md

@@ -0,0 +1,77 @@
+---
+title: Use Model Aliases for Semantic, Stable Model References
+impact: MEDIUM
+impactDescription: Hardcoded model names in client code require code changes when you swap providers; aliases let you update routing in config.yaml alone
+tags: routing, model-aliases, maintainability, client-integration
+---
+
+## Use Model Aliases for Semantic, Stable Model References
+
+`model_aliases` map human-readable names to specific model identifiers. Client applications reference the alias, not the underlying model. When you want to upgrade from `gpt-4o` to a new model, you change one line in `config.yaml` — not every client calling the API.
+
+**Incorrect (clients hardcode specific model names):**
+
+```yaml
+# config.yaml — no aliases defined
+version: v0.3.0
+
+listeners:
+  - type: model
+    name: model_listener
+    port: 12000
+
+model_providers:
+  - model: openai/gpt-4o
+    access_key: $OPENAI_API_KEY
+    default: true
+```
+
+```python
+# Client code — brittle, must be updated when model changes
+client.chat.completions.create(model="gpt-4o", ...)
+```
+
+**Correct (semantic aliases, stable client contracts):**
+
+```yaml
+version: v0.3.0
+
+listeners:
+  - type: model
+    name: model_listener
+    port: 12000
+
+model_providers:
+  - model: openai/gpt-4o-mini
+    access_key: $OPENAI_API_KEY
+    default: true
+  - model: openai/gpt-4o
+    access_key: $OPENAI_API_KEY
+  - model: anthropic/claude-sonnet-4-20250514
+    access_key: $ANTHROPIC_API_KEY
+
+model_aliases:
+  plano.fast.v1:
+    target: gpt-4o-mini          # Cheap, fast — for high-volume tasks
+
+  plano.smart.v1:
+    target: gpt-4o               # High capability — for complex reasoning
+
+  plano.creative.v1:
+    target: claude-sonnet-4-20250514  # Strong creative writing and analysis
+
+  plano.v1:
+    target: gpt-4o               # Default production alias
+```
+
+```python
+# Client code — stable, alias is the contract
+client.chat.completions.create(model="plano.smart.v1", ...)
+```
+
+**Alias naming conventions:**
+- `<org>.<purpose>.<version>` — e.g., `plano.fast.v1`, `acme.code.v2`
+- Bumping `.v2` → `.v3` lets you run old and new aliases simultaneously during rollouts
+- `plano.v1` as a canonical default gives clients a single stable entry point
+
+Reference: https://github.com/katanemo/archgw