Add std::encoding::ini module

[ChristianReifberger]

Adds a new INI parsing and encoding module to the stdlib with:

• parse()/tparse() and encode()/tencode()
• Mutations: set, remove_key, remove_section, clear, free
• Iteration: iter(), @each_key, @each (section, key, value)
• IniOptions: delimiter, padding, inline comments, duplicate-key policy
• GLOBAL section for pre-header keys
• tests covering parse, encode, round-trip, edge cases

Types

• IniMap — the parsed/constructed map; owns all allocated strings
• IniOptions — parser and encoder configuration; pass by value starting from ini::DEFAULT_OPTIONS
• DuplicateKeyBehavior — enum: DUPLICATE_OVERWRITE (default) or DUPLICATE_ERROR
• const String GLOBAL = "" — sentinel for keys before the first section header
• faultdef INVALID_SECTION, INVALID_KEY, DUPLICATE_KEY

API

Method	Description
ini::parse(allocator, src, options)	Parse INI text, heap-allocated; returns IniMap?
ini::tparse(src, options)	Parse INI text, temp-allocated; returns IniMap?
init(allocator)	Create empty map for programmatic construction
tinit()	init using temp allocator
set(section, key, value)	Insert or overwrite a key; creates section if absent
remove_key(section, key) → bool	Remove a single key; returns true if it existed
remove_section(section) → bool	Remove a section and all its keys; GLOBAL cannot be removed
get(section, key) → String?	Look up a value, or NOT_FOUND
get_section(section) → HashMap*?	Return the inner map for a section
has_section(section) → bool	True if section exists
has_key(section, key) → bool	True if key exists in section
len() → usz	Number of sections; empty GLOBAL excluded
section_len(section) → usz	Number of keys in a section, or 0 if absent
iter() → String[]	Temp-allocated slice of section names; empty GLOBAL excluded
@each_key(section; key, value)	Iterate key/value pairs within one section
@each(section, key, value)	Iterate every entry; section may be ini::GLOBAL
encode(allocator, options) → String	Serialize to INI text; global keys emitted first
tencode(options) → String	encode using temp allocator
clear()	Remove all entries; GLOBAL section kept empty
free()	Free all owned memory; safe to call after a parse error

Implementation notes

• Single file lib/std/encoding/ini.c3.
• Section names, keys, and values are all heap-copied into the provided allocator; ini::GLOBAL ("") is the one exception — it is a compile-time constant and never heap-allocated.
• The outer map is a HashMap{String, HashMap{String, String}}; each section is its own inner HashMap.
• _ensure_section copies the section name on first insertion only, so re-entering the same section is allocation-free.
• encode() writes global keys first, then named sections, using a temp-backed ByteWriter and copying the result into the target allocator at the end.
• @each in clear()/free() yields by-value copies that share backing pointers — safe because HashMap.clear()/free() never dereferences stored value internals.

Tests

test/unit/stdlib/ini.c3t covers all cases: basic parse, global keys, comments (; and #), whitespace trimming, empty values, colon delimiter, duplicate key policies (DUPLICATE_OVERWRITE / DUPLICATE_ERROR), error cases (INVALID_SECTION, INVALID_KEY), programmatic construction via init/set, mutation (remove_key, remove_section, clear), iteration (iter(), @each_key/each including GLOBAL visibility), round-trip parse → encode → parse, inline comments, CRLF line endings, and serialization options (pad_delimiter, custom delimiter).

[lerno]

The IniMap is duplicating what Object already does. Reuse Object instead. This would remove everything except the parse and encode functionality.

[ChristianReifbergerVUS]

@lerno thanks for the feedback, I've changed it to use Object. I did not look into it but you're right, much of the code could be removed

[lerno]

Also, can you make sure that this submission conforms to the rules for contributing here: https://github.com/c3lang/c3c/blob/master/CONTRIBUTING.md

[lerno]

I ended up rewriting this one significantly because the encodings should really properly be stream first. Unfortunately this is not the case for some of the older code, but new should do so.