Implement bounded repository navigation with repo-lens

- Add map, find, and around commands with repository root discovery
- Stream literal ripgrep searches with match counts and result limits
- Add direct subprocess execution and explicit error returns
- Disable C++ exceptions and add navigation tests
- Support CMake installation and document builds and deployment
- Add a reusable agent skill and document skill discovery

include/navigation.hpp

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <filesystem>
+#include <optional>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace rl
+{
+[[nodiscard]] auto repository_root(std::filesystem::path& root, std::string& error) noexcept -> bool;
+[[nodiscard]] auto number(std::string_view text) noexcept -> std::optional<std::size_t>;
+struct source_location
+{
+	std::filesystem::path file;
+	std::size_t line;
+};
+[[nodiscard]] auto parse_location(std::string_view text) noexcept -> std::optional<source_location>;
+[[nodiscard]] auto read_lines(const std::filesystem::path& file, std::vector<std::string>& lines, std::string& error) noexcept -> bool;
+auto map_sections(const std::vector<std::string>& lines, std::string_view term) -> std::string;
+} // namespace rl