feat(docs): Public API Documenter skill

- Introduced a `Public API Documenter` claude skill to audit missing KDoc in public API members.

Author: kpavlov

.claude/skills/public-api-documenter/SKILL.md

@@ -0,0 +1,58 @@
+---
+name: public-api-documenter
+description: >
+  Audit public API for missing KDoc. Use when asked to check documentation
+  coverage, find undocumented public members, or before a release to ensure
+  all public API has KDoc. Trigger for: "check kdoc", "missing docs",
+  "audit documentation", "public api docs". Skip for: test code, internal
+  modules, non-Kotlin files.
+allowed-tools: Bash(python3 ${CLAUDE_SKILL_DIR}/scripts/find-missing-kdoc.py*)
+---
+
+# Public API Documenter
+
+Audit the public API surface for missing KDoc documentation.
+
+## How to run
+
+```bash
+python3 ${CLAUDE_SKILL_DIR}/scripts/find-missing-kdoc.py
+python3 ${CLAUDE_SKILL_DIR}/scripts/find-missing-kdoc.py --verbose
+```
+
+## When to use
+
+- Before a release, to verify all public API members are documented
+- During code review, when new public API is introduced
+- When asked to "check docs", "audit kdoc", or "find missing documentation"
+
+## When to skip
+
+- Test code or internal modules — only public ABI matters
+- Non-Kotlin files or documentation-only changes
+- When the user is asking about code behavior, not documentation coverage
+
+## Exclusions
+
+The script automatically skips members that should not have KDoc:
+
+- **`override` methods/properties** — KDoc belongs on the interface or superclass
+- Auto-generated members: `equals`, `hashCode`, `toString`, `copy`, `componentN`, `serializer`, getters/setters
+- Synthetic and mangled members (inline class name-mangled signatures)
+- `Companion`, `DefaultImpls`, `$$serializer` inner classes
+
+## KDoc guidelines
+
+- Wrap KDoc to keep lines under 100 chars; wrap to multi-line if longer
+- Keep docs concise — focus on "what" and "why", not implementation details
+- Do NOT add KDoc to `override` members; document the contract on the declaring interface/superclass
+- For DSL builder internal `build()` methods (`@PublishedApi`), a one-liner is sufficient
+- For transport `start()`/`close()`/`send()`, document the lifecycle contract on the `Transport` interface
+- Don't add KDoc to data class auto-generated members
+
+## Modules checked
+
+- `kotlin-sdk-core` — Protocol types, JSON-RPC, Transport abstraction
+- `kotlin-sdk-client` — MCP client implementation
+- `kotlin-sdk-server` — MCP server implementation
+- `kotlin-sdk-testing` — In-memory test transports