Add bat syntax for WAFER / Forth 2012

Ship tools/editor-support/bat/WAFER.sublime-syntax so any bat user
(including oked, which probes bat first) renders .fth files with
proper keyword colouring, including the WAFER extras CONSOLIDATE,
RANDOM, RND-SEED, and UTIME.

Keyword list derives from register_primitive/register_host_primitive
calls in crates/core/src/outer.rs plus the boot.fth definitions.
Internal underscore-prefixed words are deliberately omitted.

Install with `just install-syntax`.

tools/editor-support/README.md

@@ -0,0 +1,47 @@
+# Editor support for WAFER
+
+Syntax highlighting assets for editors and pagers.
+
+## bat (and other Sublime-Text-compatible tools)
+
+`bat/WAFER.sublime-syntax` is a Sublime Text grammar covering Forth 2012 plus
+WAFER-specific words (`CONSOLIDATE`, `RANDOM`, `RND-SEED`, `UTIME`).
+
+### Install
+
+```
+just install-syntax
+```
+
+or manually:
+
+```
+mkdir -p ~/.config/bat/syntaxes
+cp tools/editor-support/bat/WAFER.sublime-syntax ~/.config/bat/syntaxes/
+bat cache --build
+```
+
+### Verify
+
+```
+bat --list-languages | grep -i forth        # should list Forth
+bat --language forth crates/core/boot.fth   # should render with colour
+```
+
+### Use with `oked`
+
+`oked` auto-detects `.fth` / `.4th` / `.forth` files and invokes `bat` with
+`--language forth`. After the install step above, opening any WAFER source in
+`oked` and toggling highlight (`H` command, or `oked -S forth`) will use this
+syntax.
+
+### Updating the keyword list
+
+Primitives live in `crates/core/src/outer.rs` (`register_primitive` and
+`register_host_primitive` calls). When a new **user-facing, non-standard** word
+is added, append it to the `wafer_extras` context in
+`bat/WAFER.sublime-syntax`. Standard Forth 2012 words are already covered by
+the main contexts.
+
+Internal symbols (names that start with `_`) should not be added — they are
+implementation details that user code never types.