feat(subagent): single routing resolver with persisted binding provenance (#237)

## Related Issue

No issue. Fifth step of the subagent routing work. Stacked on #236
(merge #234, #235, #236 first; until then this diff includes their
commits).

## Problem

Model selection for a new subagent lived in `planSpawn()` and again in
`resolveSubagentBinding()`, and nothing recorded why a child was bound
the way it was. A resumed child that kept an older model (created under
"main = Luna", resumed under "main = Sol") was indistinguishable from a
routing bug, and the Dynamic Workflow card had to guess.

## What changed

- `resolveSubagentModelRoute()` is the single binding authority (inherit
/ default / pool / force; `primary` override; force rejects any explicit
choice). `resolveSubagentBinding()` and the new
`SessionSubagentRoutingService` both delegate to it. `planSpawn()` is a
facade over the routing service; every plan carries `RoutingProvenance`
(`operation`, `profileSource`, `modelSource`, `policyMode`,
`policySource`, `featureSource`,
`resolvedFromRoutingEnvironmentRevision`, `routeDecisionFingerprint`).
- `SubagentBindingProvenance` is persisted once on the child (durable
agent event `subagent.binding_provenance.recorded` folded into a
replayable state key) when the child is created from a plan; forks
record `fork-inherit`. Resume reads it back: sources become
`resume-existing`, the original revision is kept, and the caller's
current `routingEnvironmentRevision` is reported alongside — never
written into the child.
- Live path: `SubagentTaskInfo`, the `subagent.spawned` event, REST
`/tasks`, the WS roster, and the session snapshot carry `routing` +
`current_routing_env_revision`; `packages/protocol` schemas and the web
client (`AppTask.routing`, `DynamicWorkflowMember`, card rows,
`keepLiveSubagents`) map them. Stable enum ids only; no display labels
on the wire.
- Durable path: the Dynamic Workflow result writes `<subagent … profile
model thinking profile_source model_source policy_mode policy_source
feature_source routing_env_revision route_decision started_at
completed_at>` through the existing attribute escaper;
`parseDynamicWorkflowResult` reads them and older results still parse.
- TUI: SDK types are additive/optional;
`agent-dynamic-workflow-progress` and `subagent-event-handler` compile
and their tests pass unchanged.
- `dist-web` rebuilt; state and wire manifests regenerated.

Tests: route matrix (inherit/default/pool/force × explicit/primary/none,
force rejects `primary`); routing service provenance for
spawn/pool/force/fork; two spawns share the environment revision and
differ in decision fingerprint; the mandatory Luna→Sol resume regression
(child stays on Luna, `resume-existing`, original revision A, current
revision B); provenance recorded exactly once per child for spawn and
fork; state fold + record guard; renderer attributes + escaping; gateway
task mapping and roster tracker; web projector, mappers, parser (new
attributes, old rows), card rows pass-through, task merge.

## Checklist

- [x] I have read the
[CONTRIBUTING](https://github.com/PyModel/pythinker-code/blob/main/CONTRIBUTING.md)
document.
- [ ] I have linked a related issue (external PRs: the issue must have a
maintainer's `/approve`).
- [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**
* Subagent tasks and workflow results now display routing details,
selected profile/model sources, policy decisions, environment revisions,
and execution timestamps.
* Routing information is preserved across spawned, forked, background,
and resumed subagent runs.
* Server metadata now exposes effective experimental feature-flag
states.

* **Bug Fixes**
* Prevented routing metadata from being overwritten or lost when task
data is merged.
* Cleared stale suspension reasons when updated suspension events omit
them.
* Ensured secondary-model settings can be explicitly cleared when no
longer available.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: elkaix

.changeset/subagent-routing-provenance.md

@@ -0,0 +1,5 @@
+---
+"@pymodel/pythinker-code": minor
+---
+
+Subagent tasks and Dynamic Workflow results now record the profile, model, and routing source of each subagent, and a resumed subagent keeps the binding it was created with.

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

@@ -1,4 +1,4 @@
 {
-  "sourceHash": "c3559f1b350b84cd73183ecca48c451946874033acb7af4738de205fdd4e4f7d",
+  "sourceHash": "e6fc28927badd164b21beb1a6062a6469618d97c34e823eaea23cbbb24594b6d",
   "sourceFileCount": 405
 }