fix: avoid intercepting quoted TOOL_NAME syntax in system tool parser

[MumuTW]

Summary

• gate non-standard TOOL_NAME: start detection so it is only allowed at the beginning of assistant output
• keep standard ```tool fenced detection unchanged
• add regression coverage to ensure explanatory/quoted tool syntax is not intercepted

Tests

• npm run vitest -- tools/systemMessageTools/toolCodeblocks/detectToolCallStart.vitest.ts tools/systemMessageTools/toolCodeblocks/interceptSystemToolCalls.vitest.ts

Closes #11070.

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Summary by cubic

Prevented the system tools parser from intercepting quoted “TOOL_NAME:” syntax by only allowing loose tool starts at the very beginning of assistant output. Standard ```tool fenced detection remains unchanged. Addresses Linear #11070.

• Bug Fixes
  • Add allowAlternateStarts option to detectToolCallStart and disable it after any non-whitespace assistant text.
  • Track non-whitespace assistant text to confine loose "TOOL_NAME:" detection to the output start.
  • Add tests to skip non-standard starts when alternates are disabled and ensure quoted/explanatory tool syntax is emitted as plain text.

^{Written for commit 71083c6. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 4 files

[MumuTW]

Pushed a formatting follow-up to address the failure.\n\n- Ran repository-configured Prettier on all PR-changed files; one test file required formatting updates.\n- Committed the fix in .\n- Re-ran targeted tests:  ERR_PNPM_NO_IMPORTER_MANIFEST_FOUND  No package.json (or package.yaml, or package.json5) was found in "/home/opc/.paperclip/instances/default/workspaces/7948d02f-b91e-4189-b9eb-32bf0b5923d2". (pass).

[MumuTW]

Pushed a formatting follow-up to address the prettier-check failure.

• Ran repository-configured Prettier on all PR-changed files; one test file required formatting updates.
• Committed the fix in 71083c6.
• Re-ran targeted tests: pnpm vitest tools/systemMessageTools/toolCodeblocks/detectToolCallStart.vitest.ts tools/systemMessageTools/toolCodeblocks/interceptSystemToolCalls.vitest.ts (pass).

[RomneyDa]

@MumuTW this one is interesting, I think the way the system prompt is formatted we would sometimes expect to see text before the tool call starts (interleaving text with tool call for lower-performance models was actually a major motivation for system tool calls). Could you provide an example for where this goes wrong or more thoughts on it?