quip: Add initial lexer sources + example ref

Signed-off-by: Ian Moffett <ian@mirocom.org>

include/frontend/lexer.h

@@ -0,0 +1,19 @@
+#ifndef FRONTEND_LEXER_H
+#define FRONTEND_LEXER_H 1
+
+#include <stdint.h>
+#include <stddef.h>
+#include "frontend/token.h"
+#include "common/state.h"
+
+/*
+ * Scan for a single token within the source file
+ *
+ * @state:   Quip state
+ * @tokres:  Token result is written here
+ *
+ * Returns zero on success
+ */
+int lexer_scan(struct quip_state *state, struct token *tokres);
+
+#endif  /* !FRONTEND_LEXER_H */

include/frontend/token.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2026, Mirocom Laboratories
+ * Provided under the BSD-3 clause
+ *
+ * Abstract:
+ *      This file defines the list of valid tokens.
+ * Author:
+ *      Ian M. Moffett <ian@mirocom.org>
+ */
+
+#ifndef FRONTEND_TOKEN_H
+#define FRONTEND_TOKEN_H 1
+
+/*
+ * Represents valid token types
+ */
+typedef enum {
+    TT_NONE,        /* [none] */
+    TT_NAME,        /* [name] */
+    TT_NEWLINE,     /* [newline] */
+    TT_COLON,       /* ':' */
+} tt_t;
+
+/*
+ * Represents a lexical token
+ *
+ * @type: Token type
+ */
+struct token {
+    tt_t type;
+    union {
+        char c;
+    };
+};
+
+#endif  /* !FRONTEND_TOKEN_H */