Add BT1035 pairing and station presets (fw 0.7.0).

Expose discoverable mode and A2DP control over REST, add persisted
DAB/FM preset list with web UI, and document gaps in docs/TODO.md.

Co-authored-by: Cursor <cursoragent@cursor.com>

Software/components/core/src/Bt1035At.cpp

@@ -13,6 +13,8 @@
 
 #include "core/Bt1035At.hpp"
 
+#include <cstdlib>
+
 namespace core {
 
 namespace {
@@ -32,6 +34,65 @@ namespace {
     return text;
 }
 
+[[nodiscard]] bool lineEqualsOk(std::string_view line) noexcept
+{
+    return trimAscii(line) == "OK";
+}
+
+[[nodiscard]] bool lineIsError(std::string_view line) noexcept
+{
+    const std::string_view trimmed = trimAscii(line);
+    return trimmed == "ERROR" || trimmed.starts_with("ERROR");
+}
+
+[[nodiscard]] bool responseContainsOk(std::string_view response) noexcept
+{
+    std::size_t start = 0;
+    while (start < response.size()) {
+        const std::size_t end = response.find_first_of("\r\n", start);
+        const std::string_view line =
+            end == std::string_view::npos
+                ? response.substr(start)
+                : response.substr(start, end - start);
+        if (lineEqualsOk(line)) {
+            return true;
+        }
+        if (end == std::string_view::npos) {
+            break;
+        }
+        start = end + 1U;
+        while (start < response.size()
+               && (response[start] == '\r' || response[start] == '\n')) {
+            ++start;
+        }
+    }
+    return lineEqualsOk(response);
+}
+
+[[nodiscard]] bool responseContainsError(std::string_view response) noexcept
+{
+    std::size_t start = 0;
+    while (start < response.size()) {
+        const std::size_t end = response.find_first_of("\r\n", start);
+        const std::string_view line =
+            end == std::string_view::npos
+                ? response.substr(start)
+                : response.substr(start, end - start);
+        if (lineIsError(line)) {
+            return true;
+        }
+        if (end == std::string_view::npos) {
+            break;
+        }
+        start = end + 1U;
+        while (start < response.size()
+               && (response[start] == '\r' || response[start] == '\n')) {
+            ++start;
+        }
+    }
+    return lineIsError(response);
+}
+
 } // namespace
 
 std::string buildBt1035AtLine(Bt1035AtCommand command)
@@ -41,6 +102,14 @@ std::string buildBt1035AtLine(Bt1035AtCommand command)
         return "AT\r\n";
     case Bt1035AtCommand::AuxLineIn:
         return "AT+AUXCFG=1\r\n";
+    case Bt1035AtCommand::PairDiscoverable:
+        return "AT+PAIR=1\r\n";
+    case Bt1035AtCommand::PairHidden:
+        return "AT+PAIR=0\r\n";
+    case Bt1035AtCommand::A2dpStat:
+        return "AT+A2DPSTAT\r\n";
+    case Bt1035AtCommand::A2dpDisconnect:
+        return "AT+A2DPDISC\r\n";
     }
     return "AT\r\n";
 }
@@ -55,6 +124,12 @@ std::array<Bt1035AtCommand, kBt1035BootInitCommandCount> bootInitSequence() noex
 
 Bt1035AtResponseKind parseBt1035AtResponse(std::string_view line) noexcept
 {
+    if (responseContainsOk(line)) {
+        return Bt1035AtResponseKind::Ok;
+    }
+    if (responseContainsError(line)) {
+        return Bt1035AtResponseKind::Error;
+    }
     const std::string_view trimmed = trimAscii(line);
     if (trimmed == "OK") {
         return Bt1035AtResponseKind::Ok;
@@ -65,4 +140,43 @@ Bt1035AtResponseKind parseBt1035AtResponse(std::string_view line) noexcept
     return Bt1035AtResponseKind::Unexpected;
 }
 
+std::expected<Bt1035A2dpState, ParseError>
+parseBt1035A2dpStatResponse(std::string_view response)
+{
+    constexpr std::string_view kPrefix = "+A2DPSTAT=";
+    const std::size_t pos = response.find(kPrefix);
+    if (pos == std::string_view::npos) {
+        return std::unexpected(ParseError::MissingField);
+    }
+
+    const std::size_t valueStart = pos + kPrefix.size();
+    char* end = nullptr;
+    const unsigned long raw =
+        std::strtoul(response.data() + valueStart, &end, 10);
+    if (end == response.data() + valueStart || raw > 5U) {
+        return std::unexpected(ParseError::MissingField);
+    }
+
+    return static_cast<Bt1035A2dpState>(raw);
+}
+
+const char* a2dpStateToken(Bt1035A2dpState state) noexcept
+{
+    switch (state) {
+    case Bt1035A2dpState::Unsupported:
+        return "unsupported";
+    case Bt1035A2dpState::Standby:
+        return "standby";
+    case Bt1035A2dpState::Connecting:
+        return "connecting";
+    case Bt1035A2dpState::Connected:
+        return "connected";
+    case Bt1035A2dpState::Streaming:
+        return "streaming";
+    case Bt1035A2dpState::Paused:
+        return "paused";
+    }
+    return "unknown";
+}
+
 } // namespace core