EPIC: release train 0.70.3 — streaming tool calls #4926

Release train 0.70.3: a patch release that carries one change, streaming tool calls (Refs #4918).

The published-path diff against v0.70.2 is the #4918 fix's files plus the version bump, and nothing else.

Route: branch release/0.70.3 cut from main where git diff --stat v0.70.2 origin/main -- crates src Cargo.toml Cargo.lock is empty. The fix lands on a topic branch cut from it, and the release PR release/0.70.3 → main merges back after the tag.

Checklist (rows of this epic; nothing is minted for them):

• A0 first reads re-measured
• A1 milestone 0.70.3 + this epic
• A2 release branch + release PR
• A3 the P0: streaming /v1/chat/completions never emits tool_calls — tool calls arrive as raw <tool_call> text in delta.content, finish_reason "stop" #4918 fix, contract, tests T1–T12
• A4 scope entry, CRUX certification copy, notes, bump, CHANGELOG (TIP)
• A5 lanes green on the TIP
• A6 tag, clean-room on the tag commit, upload, cascade 0 behind
• A7 release candidate link on P0: streaming /v1/chat/completions never emits tool_calls — tool calls arrive as raw <tool_call> text in delta.content, finish_reason "stop" #4918
• A8 live T10 receipt on main; one comment on P0: streaming /v1/chat/completions never emits tool_calls — tool calls arrive as raw <tool_call> text in delta.content, finish_reason "stop" #4918 (its close is left to its author)

#4918 stays in its current milestone until it closes.

owner: aprender-a3 (re-owned 2026-10-19 by aprender-triage-worker at the cop's word: previous owner session absent; picks up children only as batch constituents after its current timed task)