fix(llm, bootloader, embeddings): declare wippy/security and surface embedding errors

[wolfy-j]

Found while running the docs tutorials against a runtime v0.3.40a build (strict security on by default).

wippy/llm and wippy/bootloader reference a policy group they never depend on. wippy.llm.bedrock:credential_refresher.service, wippy.llm.google.oauth2:token_refresher.service and wippy.bootloader:bootloader.service declare lifecycle.security.groups: [wippy.security:process], but neither module declared an ns.dependency on wippy/security. Any application that does not add wippy/security itself fails at boot with resolve security policy group wippy.security:process: policy group not found followed by failed to execute commit protocol. Both modules now declare dep.wippy.security (>=v0.3.0; 0.3.8 already provides the group, verified by booting a service under it).

wippy/embeddings hid the real error. generate_embedding and generate_batch_embeddings ignored the error value llm.embed returns and reported every failure as Failed to generate embedding: Unknown error (EmbedResponse has no error field, so that branch was dead). They now pass the provider message through. New wippy.embeddings:embeddings_test covers the failure path: red on the old code (Unknown error), green after.

Verification on v0.3.40a (module tests run with --set security.strict_mode=false, which the wippy.test runner needs on this runtime to discover entries):

• llm 1208 passed before and after; bootloader 15/15; actor 21/21; agent 313/313.
• embeddings: 0/11 before (the suite was already broken: with nothing depending on wippy/security the bootloader failed and migrations never ran) → 12/12 after.
• Fresh app depending only on wippy/llm: wippy/security is pulled transitively, both refresher services start. With an explicit root dependency on wippy/security as well: resolves once, no conflict. Same for wippy/bootloader.
• Existing apps (app-template, kb-central) with the worktree substituted via replacements: install and boot unchanged.
• wippy lint --level error clean for llm, bootloader, embeddings; scripts/check_module_manifests.py passes.

Applications whose lock predates this change gain wippy/security on the next wippy run (online) or wippy update.

https://claude.ai/code/session_015FzmGSofbqiLD5HA6yZWDY