feat(context): carry the questions a context answers in its bundle

[tanglearncode]

The largest recall win in the routing work, and the change that makes shared contexts route the same way for everyone on a team.

The problem

A routing description answers "what is this?". Nobody searches that way — people search with the words of their problem. A context described as billing-postgres default_pool_size regression is invisible to someone asking "why was checkout throwing 5xx last week". Same incident, no shared words.

What this adds

Two optional lists on a context:

• routingQuestions — the questions it should catch, in the phrasings a user would actually type.
• routingEntities — the names inside it: services, ticket ids, error strings. The words that appear in one context and nowhere else, which is what makes them decisive.

Both are matched against and neither is ever shown to a session, so they cost nothing in the prompt and can be kept in bulk.

Why they live in the bundle

So a context handed to a teammate is findable by the same words on their machine as on yours. If this material stayed in the local routing cache, every teammate would rediscover it separately and the same context would drift into private variants. Import carries them; export already did, since it copies the manifest.

Compatibility

Both are optional, and absent rather than empty when there is nothing — a manifest should not carry a field that says only that a host did not fill it in.

• A bundle written before this existed matches on less and works exactly as before.
• A save that says nothing about them leaves what is there alone — the same rule extensions already follow — so a host that does not generate them cannot silently strip what another host wrote.

Scope

Nothing generates them yet; that is the next change. This is the storage, the indexing, and the proof that it works.

Tests

11 new. Storage and normalisation (trimming, case-insensitive de-duplication, non-string entries, a field that is not a list, the caps), update semantics in both directions, and that a change to this material counts as a routing change.

The three that matter are under what it buys: with the material, a question sharing no words with the description finds the context, and so does a bare dep-9001. Without it, the same corpus and the same question do not — which is the recall failure this exists to fix, asserted rather than asserted-about.

One earlier draft of that test was worthless and I fixed it: the context was called "Checkout incident", so the query word checkout matched the name and the test passed for the wrong reason. It is now named so that the name and description share nothing with the question.

Diff coverage: 78 changed lines, 0 uncovered. Full suite 391 passing.