feat: complete tower and subagent surfaces (#162)

## Related Issue

N/A — maintainer-authored product work.

## Problem

The desktop transcript can show duplicate live thinking activity, and
narrow subagent panels can hide the Close action. Task and subagent
outcomes also lack persisted transcript cards and model details. The
existing tower engine feature has no complete experimental client and
TUI control surface.

## What changed

- Render live thinking once and keep subagent panel actions visible at
narrow widths.
- Add escaped, persisted task outcome cards with model and
thinking-effort details.
- Add default-off tower mode across the engine, gateway, protocol, SDK,
transcript, and TUI. Enable it with
`PYTHINKER_CODE_EXPERIMENTAL_TOWER=1`.
- Add `/tower` status, teardown, toggle, and objective controls with
documentation.
- Preserve all existing Pythinker loaders; no moon-frame loader was
added.

## Verification

- `pnpm run build` and CLI bundle smoke
- `pnpm run test`: 20,392 passed, 3 expected failures, 80 skipped, 2
todo
- `pnpm run lint`, `pnpm run sherif`, root typecheck, and CI-equivalent
`tsgo`
- `pnpm --filter @pymodel/pi-tui test`: 975 passed; `pnpm -C docs run
build`
- Web asset fingerprint, flake workspace sync, and `nix build
.#pythinker-code --print-build-logs`

## Checklist

- [x] I have read the
[CONTRIBUTING](https://github.com/PyModel/pythinker-code/blob/main/CONTRIBUTING.md)
document.
- [ ] I have linked a related issue (N/A — maintainer-authored product
work).
- [x] I have added tests that prove my feature works.
- [x] Ran `gen-changesets` skill, or this PR needs no changeset.
- [x] Ran `gen-docs` skill, or this PR needs no doc update.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **New Features**
- Added experimental `/tower` mode for workspace-wide subagent
coordination, including status, enable/disable, objective, and teardown
commands.
  - Added Tower mode indicators in status views and footers.
- Added task and subagent notification cards with statuses, metadata,
output files, previews, and copy actions.
  - Added model and thinking-effort details to subagent activity.

- **Bug Fixes**
  - Removed duplicate live thinking activity.
  - Improved task completion tracking and notification handling.

- **Documentation**
  - Documented Tower mode configuration and slash commands.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: elkaix

.changeset/add-experimental-tower-command.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": minor
+---
+
+Add the experimental `/tower` command for workspace-wide subagent coordination, enabled with `PYTHINKER_CODE_EXPERIMENTAL_TOWER=1`.

.changeset/fix-desktop-subagent-activity.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Remove duplicate live activity and keep narrow subagent panel controls visible.

.changeset/show-task-outcome-cards.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": patch
+---
+
+Show task outcome cards with subagent model and thinking-effort details in conversations.

apps/pythinker-code/dist-web/.web-bundle-manifest.json

@@ -1,4 +1,4 @@
 {
-  "sourceHash": "18c3d29fcf292cd71282790f692624374551dbe7c2fbada53338814e12636327",
-  "sourceFileCount": 388
+  "sourceHash": "18d708358b92ec6e3ca36beb9975132d720096a6d1812ff94f0b3ec97ce45803",
+  "sourceFileCount": 390
 }