chore(mise): move buf to dev toolchain, keep proto tasks out of CI

buf was accidentally in base mise.toml, so CI would install it despite
having no proto tasks to run. Moved to mise.dev.toml alongside api-linter.
Both migrate to base when the API design stabilises and proto tasks enter CI.

https://claude.ai/code/session_01WX7GbU19M9fh3tAfAxzeET

Author: claude

mise.dev.toml

@@ -16,12 +16,11 @@
 
 [tools]
 watchexec = "2.5.1"
+buf = "latest"
 
 # --- Protobuf / OpenAPI (API contract is proto-first; see proto/README.md) ---
-# buf is provided by the base mise.toml tools. The proto tasks require network
-# access to buf.build (BSR deps + remote OpenAPI plugin).
-#
-# api-linter lives here (dev-only) while the API design is still in flux.
+# buf and api-linter live here (dev-only) while the API design is still in flux.
+# Move both to base mise.toml when the API stabilises and proto tasks enter CI.
 # Move it to base mise.toml once the resource shapes and method signatures
 # have stabilised and the linter output is expected to stay clean in CI.
 "github:googleapis/api-linter" = "latest"

mise.toml

@@ -16,7 +16,6 @@ experimental = true
 _.path = ["./bin"]
 
 [tools]
-buf = "latest"
 flutter = "3.44.0"
 node = "22"          # For http_server and Playwright e2e tests
 shellcheck = "0.9.0"