Bound ruff dev dependency

[freelw]

Summary

• bound the dev dependency to ruff>=0.8,<0.16
• keeps the existing lint baseline reproducible after ruff 0.16.0 began flagging hundreds of new style findings under the current config

Verification

• uv run ruff --version -> ruff 0.15.22
• uv run ruff check browser_cli lex_browser_runtime tests
• uv run pytest -q -> 527 passed
• python3 -m compileall -q browser_cli lex_browser_runtime tests
• git diff --check
• command help sweep -> 146 commands, 0 failures
• browser-cli session list --status active -> count: 0

Notes

• ruff 0.8.6, 0.12.12, 0.13.2, 0.14.6, and 0.15.0 pass on the current tree.
• ruff 0.16.0 fails with 311 findings, so this is a tooling bound rather than runtime behavior change.