docs: refine OSS weekend banner messaging

fix: update OSS weekend gating and messaging

fix(coding-agent): reuse initial resource loader on startup closes #2766

chore: approve contributor andresvi94

fix(ai): emit missing responses toolcall delta closes #2745

fix(tui): avoid overlay scrollback inflation on widen

fix(ai): detect anthropic request_too_large overflow closes #2734

docs: add switchSession to ExtensionCommandContext in extensions.md

add(coding-agent): add defineTool helper closes #2746

test(coding-agent): add session lifecycle characterization suite

test(coding-agent): add queue characterization coverage

fix(tui): stop heading underline leaking into padding

fix(tui): await async slash command completions closes #2719

fix(coding-agent): resolve theme export variables closes #2707

Enable tool streaming for newer Z.ai models (#2732)