feat: CVM relay stability fix + MCP relay integration tests

Relay disconnect fix (cvm_server.c):
- TLS read timeout reduced from 15s to 1s (short poll loop)
- Ping timer fires every 30s independently of read activity
- Consecutive timeout counter (65s) detects real disconnects
- Handle relay close frames (opcode 0x08) explicitly
- Result: 120s+ stable connection (previously ~37s disconnect cycle)

MCP relay integration tests (17/17 pass via make test-cvm-mcp):
- MCP initialize roundtrip via relay.primal.net
- get_sessions returns session array
- get_usage returns metric/price/step fields
- Non-owner auth rejection (board silently drops)
- Owner control request passes after rejection test

Build fixes:
- Remove display/font/axs15231b/qrcode deps (from display branch, not here)
- Remove local_relay/relay_selector/sync_manager deps (from relay branch)
- Add esp_timer to CMakeLists REQUIRES

Host unit tests: 61/61 pass

1 files changed, 5 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 10b7359..fba9c64 100644
--- a/Makefile
+++ b/Makefile
@@ -280,6 +280,11 @@ test-cvm:
         @echo "=== Running CVM integration test ==="
         TOLLGATE_IP=$(TOLLGATE_IP) $(NODE) tests/integration/test-cvm.mjs
 
+test-cvm-mcp:
+        $(call _require_board_lock)
+        @echo "=== Running CVM MCP relay integration test ==="
+        TOLLGATE_IP=$(TOLLGATE_IP) $(NODE) tests/integration/test-cvm-mcp-relay.mjs
+
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