chore: initial project setup with agent guide

.agent/skills/gsd-add-phase/SKILL.md

@@ -0,0 +1,39 @@
+---
+name: gsd-add-phase
+description: Add phase to end of current milestone in roadmap
+---
+
+
+<objective>
+Add a new integer phase to the end of the current milestone in the roadmap.
+
+Routes to the add-phase workflow which handles:
+- Phase number calculation (next sequential integer)
+- Directory creation with slug generation
+- Roadmap structure updates
+- STATE.md roadmap evolution tracking
+</objective>
+
+<execution_context>
+@.agent/get-shit-done/workflows/add-phase.md
+</execution_context>
+
+<context>
+Arguments: $ARGUMENTS (phase description)
+
+Roadmap and state are resolved in-workflow via `init phase-op` and targeted tool calls.
+</context>
+
+<process>
+**Follow the add-phase workflow** from `@.agent/get-shit-done/workflows/add-phase.md`.
+
+The workflow handles all logic including:
+1. Argument parsing and validation
+2. Roadmap existence checking
+3. Current milestone identification
+4. Next phase number calculation (ignoring decimals)
+5. Slug generation from description
+6. Phase directory creation
+7. Roadmap entry insertion
+8. STATE.md updates
+</process>