test: add 56 content/transport/API tests, eliminate all source warnings, add TOOLS_REFERENCE.md — bump to v0.27.5

- New test_content_transport.cpp: MCPContent factories, JSON serialization,
  MCPToolResult variants, tool annotations, transport constants, rate limiting,
  rich tool integration, dynamic lifecycle, logging levels (883 total tests)
- Fix 34 source warnings across 13 tool headers (unused params/captures)
- Add docs/TOOLS_REFERENCE.md with all 106 tools across 44 modules
- Fix README: accurate tool count (106) and test count (883)

Author: Nicola Spieser

.gitignore

@@ -18,3 +18,4 @@ test/native/test_modules
 test/native/test_auth_platform
 test/native/test_robustness
 test/native/test_session
+test/native/test_content_transport

CHANGELOG.md

@@ -2,6 +2,38 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.27.5] - 2026-02-21
+
+### Tests
+- Added **56 new content, transport & API surface tests** (`test_content_transport.cpp`):
+  - MCPContent factories: text, image, audio, resource (text & blob), empty, unicode
+  - MCPContent JSON serialization: all content types with field validation
+  - MCPToolResult: text, error, image (with/without alt), audio, chaining, empty, multi-content JSON
+  - Tool annotations: defaults, readOnly, idempotent, localOnly, custom, fluent API, JSON presence/absence
+  - Transport constants: content types, headers
+  - RateLimit: default allow, burst limiting
+  - Tool/Resource JSON: name, description, schema, handler invocation
+  - Prompt JSON: arguments serialization
+  - LogLevel: ordering, to/from string, invalid input
+  - Server rich tool integration: listing, multi-content calls, error results, audio, embedded resources
+  - Dynamic tool lifecycle: add → remove → re-add with different handler
+  - Resource template removal
+  - Version/protocol constants validation
+- **Total: 883 tests** (827 → 883)
+
+### Code Quality
+- **Eliminated all source warnings** (34 unique warnings across 13 tool headers):
+  - Added `(void)args;` for unused handler parameters in tool lambdas
+  - Added `(void)pins;` for platform-gated parameters in I2SAudioTool, LoRaTool
+  - Removed unused lambda capture `[pins]` → `[]` in LoRaTool
+  - Added `[[maybe_unused]]` to `_findPeerStats` in ESPNowTool (used only inside `#ifdef ESP32`)
+- Zero source warnings remain (mock/test warnings are expected)
+
+### Docs
+- Added `docs/TOOLS_REFERENCE.md`: auto-generated reference for all 44 tool modules (106 tools)
+- Fixed README tool count: 153 → 106 (accurate count from source)
+- Updated README test count: 827 → 883
+
 ## [0.27.3] - 2026-02-20
 
 ### Tests

README.md

@@ -33,13 +33,13 @@
 |---|:---:|:---:|:---:|
 | Runs on the MCU | ✅ | ✅ | ❌ CLI tool |
 | MCP spec compliant | ✅ 2025-03-26 | ❌ custom WS | ❌ |
-| Actually compiles | ✅ 827 tests | ❌ self-described | N/A |
+| Actually compiles | ✅ 883 tests | ❌ self-described | N/A |
 | Streamable HTTP + SSE | ✅ | ❌ | ❌ |
 | WebSocket transport | ✅ | ✅ | ❌ |
 | Claude Desktop bridge | ✅ | ❌ | ❌ |
 | mDNS discovery | ✅ | ❌ | ❌ |
 | Resource Templates (RFC 6570) | ✅ | ❌ | ❌ |
-| Built-in tools (GPIO, I2C, SPI, ADC, UART, CAN, Modbus, FS, Power, Timer, LCD, IR, RTC, Camera, ESP-NOW…) | ✅ 153 tools | ❌ | ❌ |
+| Built-in tools (GPIO, I2C, SPI, ADC, UART, CAN, Modbus, FS, Power, Timer, LCD, IR, RTC, Camera, ESP-NOW…) | ✅ 106 tools | ❌ | ❌ |
 | Sampling (server requests LLM from client) | ✅ | ❌ | ❌ |
 | Elicitation (server requests user input) | ✅ | ❌ | ❌ |
 | Audio content type | ✅ | ❌ | ❌ |