Add complete Kobo highlight sync system with NickelMenu integration

- Add text cleaning to remove page reference numbers (e.g., "10After" -> "After")
- Implement cleanHighlightText() function with boundary detection
- Add NickelMenu configuration for UI integration
- Create sync wrapper scripts (with and without FBInk notifications)
- Add installation guides for Kobo deployment
- Include pointer/slice explanation examples for learning

Features:
- Extracts highlights from Kobo SQLite database
- Cleans page references from academic texts
- Computes SHA-256 hashes for deduplication
- POSTs JSON to Flask API endpoint
- Supports ARM static linking for Kobo hardware
- Optional FBInk notifications for user feedback

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

pointer_explanation.zig

@@ -0,0 +1,28 @@
+const std = @import("std");
+
+pub fn main() !void {
+    // Example showing the conversion steps
+
+    // Step 1: SQLite gives us this type (simplified)
+    const sqlite_ptr: ?*const u8 = "hello";
+
+    // Step 2: Check if it's not null
+    if (sqlite_ptr != null) {
+        // Step 3: Cast to sentinel-terminated pointer
+        // @as(TargetType, value) - explicit type conversion
+        // [*:0]const u8 - pointer to many u8s, terminated by 0
+        const sentinel_ptr = @as([*:0]const u8, @ptrCast(sqlite_ptr));
+
+        // Step 4: Convert sentinel pointer to slice
+        // std.mem.span finds the 0 terminator and creates a slice
+        const slice: []const u8 = std.mem.span(sentinel_ptr);
+
+        std.debug.print("Slice: {s}, Length: {}\n", .{slice, slice.len});
+    }
+
+    // The one-liner version from our code:
+    const text = if (sqlite_ptr != null)
+        std.mem.span(@as([*:0]const u8, @ptrCast(sqlite_ptr)))
+    else
+        "";
+}