feat(agents): Sage launch files, lead text across seat personas, lead decision record

- agents/sage/ launch files committed after Dewey's review (R1 revise, R2
  approve). The launcher test now covers sage with its zai/glm-5.3 high pin.
  The README states the lead role and its limits, and the seat reads but
  never writes the old DYOR records under ~/.mosaic.
- N6 (Dewey authored, Sage reviewed against pins): seat personas and the
  Rocko launcher name Sage as project lead and Darkwing as a collaborating
  engineering seat, per Jason's 2026-09-26 ruling.
- docs/plans/2026-09-26_lead-decisions.md: the push, no merge into next and
  its conditions, the board restart, queue-as-data rulings, Gate F waiting
  on a T3 source, and what stays with Jason.

Launcher tests 6/6 and 1/1, eight suites green. Not pushed.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

agents/sage/README.md

@@ -0,0 +1,39 @@
+# Sage
+
+Mosaic Stack project lead (Jason's ruling, 2026-09-26). Sage coordinates
+assignments, review and integration across the repository seats under
+`agents/`. Darkwing is a collaborating seat. The lead role adds no push, merge
+or deployment authority; those still need Jason's say-so. Development sessions
+run in T3 for now, and a T3 session does not load this directory's SOUL or
+CONTEXT. This launcher is the Pi path for the same seat.
+
+From `/mnt/storage/src/mosaic-stack`:
+
+```sh
+agents/sage/launch.sh --check
+agents/sage/launch.sh
+agents/sage/launch.sh --fresh
+```
+
+`--check` validates configuration/context and the pinned local Pi version without
+launching a TUI, registering a seat, requesting authentication or calling a model.
+Normal launch registers the repository seat through `scripts/mosaic`, then uses
+the existing host-development helper with `zai/glm-5.3` and high thinking by
+default; provider, model and thinking flags can be overridden per launch. It
+resumes validated per-agent conversation state under `.pi/state/sage`; `--fresh`
+starts another conversation without deleting history. Existing launcher locking
+prevents duplicate native instances.
+
+Bootstrap configuration remains authoritative. Missing config, context or pinned
+dependencies fails closed. No configuration or credentials are copied from a fleet
+seat, and this launcher modifies no files under `~/.mosaic`. A separate fleet Sage
+seat under `~/.mosaic` is being decommissioned and does not speak for this seat.
+
+Sage's earlier DYOR strategy role is retained as records only. Those records sit in
+the fleet Sage tree under `~/.mosaic`, which this seat reads but does not write.
+Whether DYOR strategy work continues, and where its new records live, is Jason's
+call.
+
+Offline launcher tests (`scripts/test-darkwing-launch.mjs`) use a fake Pi and
+isolated registration/session directories. Live startup and provider
+authentication are separate observations, not implied by passing tests.