code_size: run report and diff on Windows

.claude/skills/code-size/SKILL.md

@@ -14,7 +14,7 @@ description: Use when sizing TinyUSB examples per file, section or symbol (repor
 | all examples, CI-pinned, combined | `python3 tools/code_size.py diff --ci`                         |
 | one tree, no diff                 | `python3 tools/code_size.py report -b BOARD -e device/cdc_msc` |
 
-By default the base comes from the master snapshots CI stored for `--base-branch`'s commit (`--baseline-repo`, default `hathach/tinyusb`, through your `gh` login; cached per master run in `${XDG_CACHE_HOME:-~/.cache}/tinyusb/code-size-baseline/`, shared by every checkout), else its nearest first-parent ancestor's; the `Base:` line names the commit used and how far back it is, and master changes after it count as yours. `--base-branch` means its tip; pass a merge-base SHA to diff against that. When the CI base cannot be had (no `gh` or login, no stored run within 30 commits, a base off master, a failed download) or `-f`, `--bloaty` or another `--engine` needs an elf, the base is built locally in a temporary worktree and the report's `Base:` line says why; `--base-source ci` fails instead, `--base-source local` always builds and makes no GitHub call. Against a CI base, a board whose compiler or membrowse version differs from yours, or is unknown, is still compared with a warning naming both. A local diff never builds CI's `-DMA` variants; DMA-path changes are measured only by the PR's CI comment. A local base worktree symlinks this checkout's fetched dependencies, so a `tools/get_deps.py` pin bump's own size change is not in its diff, while a CI base was built with CI's. A local `report` or `diff` cannot size a `-D` variant build.
+By default the base comes from the master snapshots CI stored for `--base-branch`'s commit (`--baseline-repo`, default `hathach/tinyusb`, through your `gh` login; cached per master run in `${XDG_CACHE_HOME:-~/.cache}/tinyusb/code-size-baseline/` (`%LOCALAPPDATA%` on Windows), shared by every checkout), else its nearest first-parent ancestor's; the `Base:` line names the commit used and how far back it is, and master changes after it count as yours. `--base-branch` means its tip; pass a merge-base SHA to diff against that. When the CI base cannot be had (no `gh` or login, no stored run within 30 commits, a base off master, a failed download) or `-f`, `--bloaty` or another `--engine` needs an elf, the base is built locally in a temporary worktree and the report's `Base:` line says why; `--base-source ci` fails instead, `--base-source local` always builds and makes no GitHub call. Against a CI base, a board whose compiler or membrowse version differs from yours, or is unknown, is still compared with a warning naming both. A local diff never builds CI's `-DMA` variants; DMA-path changes are measured only by the PR's CI comment. A local base worktree symlinks this checkout's fetched dependencies, so a `tools/get_deps.py` pin bump's own size change is not in its diff, while a CI base was built with CI's. A local `report` or `diff` cannot size a `-D` variant build.
 
 ## Setup and choices
 
@@ -25,6 +25,7 @@ Flags and syntax: `python3 tools/code_size.py <command> --help`. The choices:
 - `--symbols` when Flash/RAM cancel: a pair counts as changed when its sections or symbols moved.
 - `--ci` for "all boards" / "CI"; it needs the arm, riscv, msp430 and ft9xx toolchains, and ESP-IDF or docker.
 - An espressif board builds each example `tools/build.py` picks as its own ESP-IDF project: with the exported ESP-IDF (`. "$IDF_PATH/export.sh"`), else in CI's image through docker, as your user (once: `docker pull espressif/idf:v5.5.3 && docker tag espressif/idf:v5.5.3 espressif/idf:tinyusb`, about 8.4 GB).
+- Windows: run `python -X utf8 tools/code_size.py …` (or set `PYTHONUTF8=1`), else redirected output fails on `Δ`. `report` and `diff` work for paths without spaces, and a non-ASCII checkout, CMake or toolchain path needs ninja >= 1.11 whose `ninja -t wincodepage` reports UTF-8; espressif boards are refused. A local base, including the fallback, symlinks its dependencies: enable Developer Mode unless running elevated.
 
 ## Results