test(coderd/x/chatd): move the Anthropic guard unit test into chatsanitize - #30969

Renames coderd/x/chatd/anthropic_guard_test.go to coderd/x/chatd/chatsanitize/anthropic_guard_test.go and moves the ten helpers only TestAnthropicProviderToolPreRequestGuard uses from chatd_test.go into it. The test now lives in chatsanitize, the package it tests.

Why it is safe

This is a pure move. The only changed lines are the package clause (chatd_test to chatsanitize_test) and the chatsanitize import that chatd_test.go no longer needs. Git records the file as a rename (R056).

• Every moved helper had no other caller in package chatd_test (git grep -nw per name), and none collides with a name in chatsanitize_test.
• Purity check: the sorted -/+ diff prints only the package clause and the removed import. git diff --color-moved=plain marks all 128 moved helper lines as moved and leaves those 3 lines unmarked.
• The same four subtests pass in ./coderd/x/chatd/chatsanitize/ as before in ./coderd/x/chatd/.

Review focus

Confirm that the helpers arrived unchanged. git diff -M --color-moved=plain shows it.

Validation

• go test ./coderd/x/chatd/chatsanitize/... -count=1 and -run '^TestAnthropicProviderToolPreRequestGuard$' -v: pass, same 4 subtests.
• go vet ./coderd/x/chatd/ ./coderd/x/chatd/chatsanitize/: clean.
• Pre-commit hook: passed.

Stack

This stack moves the Anthropic guard unit test into chatsanitize, then deletes the guard escalation that can never repair a prompt.

1. test(coderd/x/chatd): move the Anthropic guard unit test into its own file #30968 Move the Anthropic guard unit test into its own file
2. test(coderd/x/chatd): move the Anthropic guard unit test into chatsanitize #30969 Move the Anthropic guard unit test into chatsanitize
3. refactor(coderd/x/chatd/chatsanitize): drop Anthropic guard escalation passes #30970 Drop the Anthropic guard escalation passes

Xum, an AI agent, opened this PR for @ibetitsmike and wrote this description.