Bootstrap Rivencraft for NeoForge 1.21.1

docs/PORTING.md

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+# Porting plan
+
+Mystcraft Legacy contains more than 700 Java source files and targets Minecraft
+1.12.2. The Minecraft world-generation, dimension, registry, networking, and
+rendering APIs have all changed substantially since that release. The port is
+split into independently testable milestones.
+
+## Milestones
+
+1. **Bootstrap** — NeoForge 1.21.1 build, mod metadata, item registration, and
+   CI. (In progress.)
+2. **Books and linking** — descriptive/linking book data components, lectern-like
+   interaction, safe teleportation, and return links.
+3. **Ages** — dimension definitions backed by data packs, deterministic seeds,
+   lifecycle management, and persistence.
+4. **Writing system** — pages, symbols, notebooks, desks, and book assembly.
+5. **Age grammar** — translate symbol combinations into modern biome, noise,
+   dimension-type, and worldgen configuration.
+6. **Instability** — deterministic validation and effects with server-safe
+   behavior.
+7. **Structures and polish** — libraries, crystals, portals, recipes, models,
+   sounds, advancements, compatibility, and migration tests.
+
+## Provenance rules
+
+- New code uses the `net.dnorberg.rivencraft` package.
+- Adapted Mystcraft code must retain its upstream copyright notice and be
+  tracked in this document or a nearby source comment.
+- Do not copy generated, binary, or third-party dependency content from the
+  legacy repository.
+- Preserve LGPL-3.0-or-later compatibility for the complete distributed mod.
+
+## First vertical slice
+
+The first functional target is: create a Descriptive Book, bind it to one
+server-managed Age definition, travel to that Age, and use a Linking Book to
+return. This exercises persistence, networking, dimensions, and safety before
+the symbol grammar is introduced.