docs: follow-ups to the snippet audit (docs-site pages missing canisterId, v8-only idleOptions JSDoc, stale example headers, CanisterError.details type)

[b3hr4d]

Follow-ups from the AI-context and README snippet audit (#674–#679). The audit fixed the llms files, the skills and the package READMEs; these are the same defects elsewhere, plus one possible library issue.

1. The docs site repeats some README defects. tanstack-router.mdx calls the hooks/ files "generated", but current codegen doesn't write them. cli.mdx doesn't document the per-canister canisterId option, and without it the generated reactor throws on import in Node and on a deployed site (docs(cli): the README's example config generates a reactor that throws on import; the canisterId option is undocumented #677). Other pages may also be missing canisterId in their setup snippets (docs(ai-context): llms-full.txt and the hooks skill teach setups that throw, a nonce that fails tsc, and "generated" files codegen no longer writes #674).
2. JSDoc. defineReactor's auth option and idleOptions don't say that idleOptions works only with @icp-sdk/auth v8. v10 drops it with a warning.
3. Example headers. The legacy examples/tanstack-router hook files still carry "Auto-generated by @ic-reactor/cli" headers, although codegen no longer produces them.
4. Possible library issue, unproven. CanisterError.details is typed as a Map, but it holds whatever the canister's details field was. Check it against real canister error shapes. If the type is wrong, fix it in core.
5. Skills repository. The separate B3Pay/ic-reactor-skills copy of SKILL.md needs the same changes as docs(ai-context): llms-full.txt and the hooks skill teach setups that throw, a nonce that fails tsc, and "generated" files codegen no longer writes #674. It lives in another repository, so it's listed here for the maintainer.

Acceptance

• Items 1–3 are corrected. Snippets are type-checked the way docs(ai-context): llms-full.txt and the hooks skill teach setups that throw, a nonce that fails tsc, and "generated" files codegen no longer writes #674's audit did.
• Item 4 is either confirmed with a test that fails on main and fixed, or shown to be correct.

[b3hr4d]

Items 1–3 are fixed in #687 and item 4 in #688, both merged. Only item 5 is left: the B3Pay/ic-reactor-skills copy of SKILL.md needs the #674/#680 changes. It lives in another repository, so it's for the maintainer.