docs(coding): files 1000 lines max, functions 200 lines max, no earlier split point

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

code-languages/rust.md

@@ -73,8 +73,12 @@ workspace = true
   wrong for the *entire* codebase — not a shortcut for one stubborn call site. It silences
   the rule in code nobody has written yet.
 - **Re-test every `#[allow]` periodically.** If removing one produces no warning, delete it.
-- `too_many_lines` is the mechanical enforcement of the 100-line function limit. A function
-  that trips it wants extracting, not an allow.
+- `too_many_lines` is the mechanical enforcement of the 200-line function limit. Clippy's
+  default threshold is 100, so set it in `clippy.toml`:
+  ```toml
+  too-many-lines-threshold = 200
+  ```
+  A function that trips it wants extracting, not an allow.
 - Clippy has **no file-length lint**, so the 1000-line file limit belongs in a test — see
   [`coding-dev.md` §4](skills-public/coding-dev.md) for the pattern. Put it in the workspace
   root's `tests/` so one test covers every member crate, walking `src/` plus each