Registration macros fail to compile for namespace-qualified model/action types

[Yaraslaut]

Summary

BRIDGE_REGISTER_MODEL / BRIDGE_REGISTER_ACTION build the name of their generated
static registrar by token-pasting the model and action types:

[[maybe_unused]] const bool bridge_action_reg_##M##_##A = ...

That works only when both arguments are bare identifiers. Passing a qualified type
pastes into an invalid preprocessor token and fails to compile.

Reproduction

namespace app::models {

struct Report {
    struct Create {
        static constexpr std::string_view Name = "Create";
        struct Payload { int id = 0; };
        struct Result  { bool ok = false; };
        using ReturnType = Result;
        Payload payload;
    };

    Create::Result execute(Create const&);
};

} // namespace app::models

// Unqualified — fine:
//   BRIDGE_REGISTER_MODEL(Report, "Report")

// Qualified — fails: the generated identifier contains ':' characters.
BRIDGE_REGISTER_MODEL(app::models::Report, "app.models.Report")
BRIDGE_REGISTER_ACTION(app::models::Report, app::models::Report::Create, "Create")

MSVC / clang-cl reject the pasted token; the error points at the macro expansion rather
than at the call site, which makes it slow to diagnose.

Why it matters

Any codebase that namespaces its models — or nests action types inside the model struct,
which the documented action shape encourages — cannot use the registration macros without
introducing a local alias purely to dodge the paste:

using ReportModel = app::models::Report;   // only exists to satisfy the macro
BRIDGE_REGISTER_MODEL(ReportModel, "app.models.Report")

The existing tests and examples all register unqualified types, so this never shows up
in-tree.

Suggested fix

Key the generated names on __LINE__ instead of on the type spelling. There is exactly
one registration per line, so it is equally unique, and it is independent of how the type
is written:

#define BRIDGE_DETAIL_CAT_(a, b) a##b
#define BRIDGE_DETAIL_CAT(a, b)  BRIDGE_DETAIL_CAT_(a, b)

[[maybe_unused]] const bool BRIDGE_DETAIL_CAT(bridge_action_reg_, __LINE__) = ...

Strictly more permissive: no behaviour change for existing callers, and unqualified
registrations keep compiling unchanged.

I'm happy to open a PR if the approach looks right.