ci: migrate project automation to Just (#442)

* ci: migrate project automation to Just

Centralize build, test, release, dependency, hook, and website commands in Just recipes. Pin workflow tooling, use the repository toolchain, and run the complete validation set in CI.

* ci: codex being codex

* docs: update CLAUDE.md for just task runner migration

Reflect the switch to just recipes for build/test/clippy/fmt, note
dprint replacing raw rustfmt, and add a cross-platform code requirement.

* fix: resolve clippy warnings breaking CI on ubuntu and windows

Use clone() instead of implicit to_string() on already-owned String
values, gate the windows-only unused make_file_at import behind
cfg(posix), and fix unused mut / manual assign-op in the windows-only
localhost test.

* fix: fmt

CODE_OF_CONDUCT.md

@@ -17,23 +17,23 @@ diverse, inclusive, and healthy community.
 Examples of behavior that contributes to a positive environment for our
 community include:
 
-* Demonstrating empathy and kindness toward other people
-* Being respectful of differing opinions, viewpoints, and experiences
-* Giving and gracefully accepting constructive feedback
-* Accepting responsibility and apologizing to those affected by our mistakes,
+- Demonstrating empathy and kindness toward other people
+- Being respectful of differing opinions, viewpoints, and experiences
+- Giving and gracefully accepting constructive feedback
+- Accepting responsibility and apologizing to those affected by our mistakes,
   and learning from the experience
-* Focusing on what is best not just for us as individuals, but for the overall
+- Focusing on what is best not just for us as individuals, but for the overall
   community
 
 Examples of unacceptable behavior include:
 
-* The use of sexualized language or imagery, and sexual attention or advances of
+- The use of sexualized language or imagery, and sexual attention or advances of
   any kind
-* Trolling, insulting or derogatory comments, and personal or political attacks
-* Public or private harassment
-* Publishing others' private information, such as a physical or email address,
+- Trolling, insulting or derogatory comments, and personal or political attacks
+- Public or private harassment
+- Publishing others' private information, such as a physical or email address,
   without their explicit permission
-* Other conduct which could reasonably be considered inappropriate in a
+- Other conduct which could reasonably be considered inappropriate in a
   professional setting
 
 ## Enforcement Responsibilities