General purpose library with functions and classes usable in many projects, covering c-string handling, conversions and in- or output.

This library provides a small set of lightweight utilities tailored for Arduino-style environments. The focus is on minimal allocations, explicit buffer usage, and support for strings stored in RAM or PROGMEM.

• String handling: strref for read-only string views across RAM/PROGMEM/Arduino String, plus str<N> as a fixed-size string buffer.
• Formatting: Formatter and format() helpers for safe, bounded printf-style formatting into user-managed buffers.
• Optional values: Maybe<T> as a compact alternative to std::optional, with basic combinators.
• Conversions: convert<T> for parsing and formatting common primitive types, plus boolean format variants.
• Decimal numbers: Decimal for fixed-point style decimal I/O backed by a 64-bit integer.
• Fixed-capacity map: FixedCapacityMap<K, V, N> for sorted key/value storage with deterministic memory usage.
• Streams: Minimal IInput/IOutput interfaces, string- and stream-backed adapters, and InputStream for bridging to Arduino Stream APIs.
• Repository transactions: Transaction<R> and beginTransaction() helpers for simple commit/rollback patterns.

• Some conversions and formatting APIs reuse internal buffers; treat returned strings as transient unless you provide your own buffer.
• PROGMEM strings are supported through strref to avoid redundant copies.