Added Kitty Graphics Protocol support for eterm module, still a WIP but working.

docs/articles/eterm-kitty-graphics.md

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+# eTerm Kitty graphics protocol
+
+eTerm implements the terminal-receiver side of the Kitty graphics protocol. Protocol parsing,
+decoding, image storage, placement state, animation, and terminal lifecycle integration run on the
+terminal worker. The UI thread consumes immutable placement metadata and an ordered pixel-update
+stream, and exclusively owns the OpenGL texture cache.
+
+## Supported features
+
+- direct RGB and RGBA transmission, including chunking and zlib compression;
+- PNG transmission;
+- image IDs, image numbers, placement IDs, source cropping, cell geometry, and pixel offsets;
+- root-image rectangle updates, animation frames, frame composition, and animation control;
+- deletion selectors, quiet modes, capability queries, storage quotas, usage hints, and eviction;
+- primary/alternate-screen state, reset, clear, scrolling, margins, scrollback, and resize;
+- Unicode placeholder placements (U+10EEEE and Kitty's combining-diacritic encoding);
+- relative placements, including parent validation, cycle detection, and descendant movement;
+- terminal pixel-size queries and SGR pixel mouse coordinates.
+
+Local file, temporary-file, and shared-memory transfer media are intentionally not enabled. Direct
+transmission is the portable path and works through SSH without giving terminal applications access
+to the terminal host's filesystem or shared-memory namespace.
+
+## Resource and threading behavior
+
+Decoded root images are stored as premultiplied-independent RGBA8 CPU buffers on the worker. GPU
+textures exist only on the UI/GL thread. Incremental updates carry monotonically increasing sequence
+numbers; a bounded queue gap triggers a complete graphics resynchronization. Image count, placement
+count, APC size, decoded transfer size, and total image storage are bounded. Unreferenced images are
+evicted oldest-first when storage is needed.
+
+Graphics follow the same presentation cadence and DEC synchronized-update boundary as text. A
+placement anchored in normal-screen history moves with terminal scrolling and is projected into the
+current scrollback viewport. Margin scrolling clips or removes only placements wholly participating
+in the scrolled region. Resize preserves screen-coordinate placements and reflows Unicode placeholder
+metadata with its text cells.
+
+## Compatibility testing
+
+The eTerm unit suite covers fragmented APC input, malformed/fuzzed commands, raw/zlib/PNG transfer,
+independent image namespaces, replacement, partial updates, placement geometry, scrolling and
+scrollback, screen lifecycle, animation, Unicode placeholders, relative placement graphs, ordered
+worker/UI delivery, queue overflow, and resynchronization.