GeezerVison

Adds Gemini CLI as a framework harness alongside Claude Code and Codex:

- convert_gemini_cli_to_agentex_events: maps the CLI's stream-json events
  (init, message deltas, tool_use, tool_result, error, result; schema per
  packages/core/src/output/types.ts in google-gemini/gemini-cli) onto the
  canonical StreamTaskMessage* stream. Assistant deltas open one text slot
  that closes on the next tool event, the result, or end of stream, so every
  Start has a Done; tool requests and results pair by tool_id.
- GeminiCliTurn: HarnessTurn wrapper exposing session_id and model from the
  init event and normalising result.stats into TurnUsage.
- Both exported from agentex.lib.adk.
- agentex init templates sync-gemini-cli, default-gemini-cli and
  temporal-gemini-cli (registered in TemplateType, file map and menus),
  cloned from the Claude Code templates: prompt passed via -p with stdin
  closed (the CLI reads stdin to EOF in headless mode), optional GEMINI_MODEL,
  GEMINI_API_KEY credential, npm install -g @google/gemini-cli in the
  Dockerfile. Turns are independent prompts: the CLI's --resume takes
  latest/index, not a session id.
- Tests: tap (text deltas, whole messages, tools, errors, callbacks,
  source close on cancel), turn (usage mapping, protocol), harness end to
  end through UnifiedEmitter with span derivation; template suite covers the
  three new templates.

Offline tests only; a live smoke run needs a Gemini API key.

Claude-Session: https://claude.ai/code/session_01HCVKnA7LeJZ44nxZz1uzF3

…silently

A terminal `result` with `status: "error"` (auth failure, turn limit, fatal
tool error) went straight to `on_result`, so UnifiedEmitter delivered the
turn as an ordinary completion with partial or no output. Deliver it as a
TextContent error message before firing `on_result`, the same shape the
Codex tap uses for `turn.failed`. Standalone `error` events with severity
"error" are delivered the same way; warnings are still only logged.

…ines

- Read stdout with an 8 MiB line limit. A tool_result that echoes a file is
  one stream-json line, and asyncio's 64 KiB default made readline() raise
  and abort the turn.
- After SIGTERM, wait at most 5 s for the CLI to exit, then SIGKILL, so a
  CLI that ignores SIGTERM cannot hang request or activity cancellation.
- Match the sibling templates on current main: the optional private index
  step in both Dockerfiles, and make_workflow_logger in the Temporal workflow.
- Fix "Gemini CLI CLI" wording.

Verified with a fake `gemini` that prints a 100,000-character line and
ignores SIGTERM: the line is read whole and aclose() returns after 5 s.

pyright 1.1.399 (the locked version `scripts/lint` runs) reported six
errors in the Gemini CLI tests: attribute access on a content union after
a list-comprehension filter, which does not narrow the indexed element,
and aclose() on the tap's AsyncIterator return type. Assert the concrete
content type before reading it, and cast the tap to AsyncGenerator where
the test closes it. Test behaviour is unchanged.