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-preferences.md

@@ -0,0 +1,73 @@
+---
+title: Write Task-Specific Routing Preference Descriptions
+impact: HIGH
+impactDescription: Vague preference descriptions cause Plano's internal router LLM to misclassify requests, routing expensive tasks to cheap models and vice versa
+tags: routing, model-selection, preferences, llm-routing
+---
+
+## Write Task-Specific Routing Preference Descriptions
+
+Plano's `plano_orchestrator_v1` router uses a 1.5B preference-aligned LLM to classify incoming requests against your `routing_preferences` descriptions. It routes the request to the first provider whose preferences match. Description quality directly determines routing accuracy.
+
+**Incorrect (vague, overlapping descriptions):**
+
+```yaml
+model_providers:
+  - model: openai/gpt-4o-mini
+    access_key: $OPENAI_API_KEY
+    default: true
+    routing_preferences:
+      - name: simple
+        description: easy tasks      # Too vague — what is "easy"?
+
+  - model: openai/gpt-4o
+    access_key: $OPENAI_API_KEY
+    routing_preferences:
+      - name: hard
+        description: hard tasks      # Too vague — overlaps with "easy"
+```
+
+**Correct (specific, distinct task descriptions):**
+
+```yaml
+model_providers:
+  - model: openai/gpt-4o-mini
+    access_key: $OPENAI_API_KEY
+    default: true
+    routing_preferences:
+      - name: summarization
+        description: >
+          Summarizing documents, articles, emails, or meeting transcripts.
+          Extracting key points, generating TL;DR sections, condensing long text.
+      - name: classification
+        description: >
+          Categorizing inputs, sentiment analysis, spam detection,
+          intent classification, labeling structured data fields.
+      - name: translation
+        description: >
+          Translating text between languages, localization tasks.
+
+  - model: openai/gpt-4o
+    access_key: $OPENAI_API_KEY
+    routing_preferences:
+      - name: code_generation
+        description: >
+          Writing new functions, classes, or modules from scratch.
+          Implementing algorithms, boilerplate generation, API integrations.
+      - name: code_review
+        description: >
+          Reviewing code for bugs, security vulnerabilities, performance issues.
+          Suggesting refactors, explaining complex code, debugging errors.
+      - name: complex_reasoning
+        description: >
+          Multi-step math problems, logical deduction, strategic planning,
+          research synthesis requiring chain-of-thought reasoning.
+```
+
+**Key principles for good preference descriptions:**
+- Use concrete action verbs: "writing", "reviewing", "translating", "summarizing"
+- List 3–5 specific sub-tasks or synonyms for each preference
+- Ensure preferences across providers are mutually exclusive in scope
+- Test with representative queries using `planoai trace` and `--where` filters to verify routing decisions
+
+Reference: https://github.com/katanemo/archgw