phase 0: scaffold workspace, plugin layout, and CI

Lay down the empty repo skeleton defined in SPEC.md §5 so subsequent
phases have somewhere to land:

- Cargo workspace (resolver v2, edition 2021, MSRV 1.83) with
  nuwiki-core, nuwiki-lsp, nuwiki-ls — dep direction matches §6.2.
- Vim/Neovim plugin directory layout (plugin, lua, autoload, ftdetect,
  ftplugin, syntax, doc, scripts) with header-only stubs.
- .gitea/workflows/ci.yaml running fmt, clippy -D warnings, and tests
  pinned to Rust 1.83.
- README, dual MIT/Apache-2.0 license texts, .gitignore.

Verified: cargo check / fmt --check / clippy / test all clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/nuwiki-ls/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "nuwiki-ls"
+description = "nuwiki language server binary — speaks LSP over stdio."
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+authors.workspace = true
+license.workspace = true
+repository.workspace = true
+homepage.workspace = true
+
+[lints]
+workspace = true
+
+[[bin]]
+name = "nuwiki-ls"
+path = "src/main.rs"
+
+[dependencies]
+nuwiki-lsp = { path = "../nuwiki-lsp", version = "0.1.0" }

crates/nuwiki-ls/src/main.rs

@@ -0,0 +1 @@
+fn main() {}