Add safe managed lifecycle for generated host bundles

[ScriptedAlchemy]

Summary

Move from build-only host artifacts to an optional, receipt-backed lifecycle:
preview, install, update, repair, uninstall, rollback, recovery, and Doctor
verification. Preserve unrelated host configuration and apply component sets
atomically.

Problem

Generating valid plugin directories is insufficient for complex integrations.
Hosts may own shared JSON/TOML registries, require their own CLI installer,
prompt for trust, stage a plugin before activation, or use native extension
directories. Updating one component must not remove another or overwrite
third-party settings.

TraceDecay currently implements these guarantees itself. Agent Bundle should
make them a reusable framework capability after the host component compiler
can describe exact ownership.

Lifecycle

inspect observed state
  -> preview immutable mutation plan
  -> require exact confirmation digest
  -> backup owned/shared documents
  -> apply component transaction
  -> host-specific activation
  -> verify native registration and artifact bytes
  -> publish receipt

Supported operations:

• install;
• update;
• repair;
• uninstall;
• rollback to the prior confirmed component set;
• recover an interrupted journal.

Safety requirements

• safe, canonical install roots with symlink/path-escape refusal;
• content digests and ownership markers per artifact;
• exact preview/apply revision pairing;
• component-scoped backups and receipts;
• atomic or journaled multi-file writes;
• structured merges that preserve unrelated host keys;
• host CLI registration where the host owns its registry;
• competing-extension detection;
• explicit manual-activation state where automation is unavailable;
• no credentials in manifests, receipts, or logs.

Doctor

Doctor reports each component as installed, missing, repairable, deferred,
conflicted, unavailable, or corrupt. It verifies:

• artifact content and provenance;
• native host registration;
• activation/trust state where observable;
• protocol/runtime compatibility;
• receipt and backup integrity;
• stale or interrupted journal recovery.

Non-goals

• Claiming installation merely because files were generated.
• Replacing a shared host configuration wholesale.
• Remotely distributed third-party bundles without a separate trust model.
• Automatically trusting hooks or extensions on the user's behalf.

Acceptance criteria

• Dry run opens no writer and reports exact planned paths and shared-config
  mutations.
• Install and update preserve unrelated host configuration.
• An interrupted multi-component install recovers or rolls back safely.
• Repair restores owned artifacts without adopting foreign paths.
• Uninstall removes only receipt-owned artifacts and registrations.
• Doctor distinguishes activation deferred from installed-and-active.
• At least two materially different host registration mechanisms pass real
  lifecycle tests.

Design references

• Current Agent Bundle artifact plan boundary
• TraceDecay host-bundle lifecycle design
• TraceDecay receipt-backed host bundle implementation
• TraceDecay capability admission and verification
• VS Code extension model as one native activation surface

Stack position

• Depends on: #100 capability-aware host components.
• Independent of #98 application state; this manages plugin deployment,
  not application data.

Full meta-framework stack

• Foundations: #93 routes - #94 identity - #95 context - #96 renderer
• Runtime: #97 events - #98 state - #99 notices
• Host: #100 components - #101 lifecycle
• Surfaces and proof: #102 CLI/scripts - #103 Rstest - #104 proximity example - #105 Workbench