feat: initial scaffold kanban_cpp v0.1.0

C++ ImGui kanban for steering LLM agents. Six panels (Board, Calendar,
Dashboard, Agent runs, Worktrees, DoD inspector) wired to registry
functions http_request, kpi_card, sparkline, agent_runs_timeline,
dod_evidence_panel. Backend Go on :8403 (independent operations.db from
kanban_web).

data.h

@@ -0,0 +1,61 @@
+// data.h — HTTP client wrapper for kanban_cpp backend at :8403.
+//
+// Wraps fn_http::request() (cpp/functions/core/http_request.h) with
+// kanban-specific shapes (Card, Column, AgentRunSummary).
+#pragma once
+
+#include <string>
+#include <vector>
+#include <cstdint>
+
+namespace kanban_cpp {
+
+struct Card {
+    std::string id;
+    std::string title;
+    std::string description;
+    std::string column_id;
+    std::string priority;       // low|medium|high|critical
+    std::string status;         // pending|doing|done|...
+    int64_t     position = 0;
+    int64_t     due_date = 0;   // unix seconds, 0 = no due
+    std::string assignee;
+    std::vector<std::string> labels;
+};
+
+struct Column {
+    std::string id;
+    std::string name;
+    int         order = 0;
+};
+
+struct AgentRunSummary {
+    std::string id;
+    std::string card_id;
+    std::string branch;
+    std::string status;
+    int64_t     started_at = 0;
+    int64_t     finished_at = 0;
+};
+
+struct ClientConfig {
+    std::string base_url = "http://127.0.0.1:8403";
+    std::string agent_runner_url = "http://127.0.0.1:8486";
+    int         timeout_ms = 3000;
+};
+
+// HTTP GETs ---------------------------------------------------------------
+std::vector<Card>    list_cards(const ClientConfig& cfg, std::string& err);
+std::vector<Column>  list_columns(const ClientConfig& cfg, std::string& err);
+bool                 health(const ClientConfig& cfg);                          // GET /health
+
+// HTTP mutations ----------------------------------------------------------
+bool move_card(const ClientConfig& cfg, const std::string& card_id,
+               const std::string& new_column_id, std::string& err);
+
+// agent_runner_api -------------------------------------------------------
+std::vector<AgentRunSummary> list_runs(const ClientConfig& cfg, std::string& err);
+bool launch_workflow(const ClientConfig& cfg, const std::string& card_id,
+                     std::string& out_run_id, std::string& err);
+
+} // namespace kanban_cpp