fix(FunctionResult): tap direction is speak/listen/both, and always emitted

[grandcamel]

Summary

FunctionResult.tap() disagreed with the SWML schema (and the live platform docs, https://signalwire.com/docs/swml/reference/tap) in two ways, both of which made it emit taps that don't do what the caller asked:

1. "hear" is not a SWML direction. The verb's enum is speak | listen | both; the helper accepted and emitted "hear". A tap(uri, direction="hear") produced SWML the platform rejects. record_call() in the same class already uses the correct ("speak", "listen", "both") set — tap was the outlier.

2. The omit-if-default logic assumed the platform default is "both"; it's "speak". The helper only emitted direction when it differed from its own "both" default, so tap(uri) — documented as tapping both directions — actually produced a speak-only tap. The codec/rtp_ptime omissions are unaffected (their helper defaults match the schema defaults).

Fix

• direction is now Literal["speak", "listen", "both"], matching record_call and the schema. "hear" now raises the existing ValueError — it could never produce a working tap, so no working caller regresses; a broken silent tap becomes a loud error.
• direction is always emitted, so the helper's documented "both" default is what the platform actually executes.
• docs/swaig_reference.md and docs/api_reference.md updated to match (api_reference had a third wrong enum — "inbound"/"outbound" — plus a G722 codec and sip: URIs the helper never accepted).

Behavior note (please review)

For existing callers of tap(uri) with no explicit direction, emitted SWML changes from (no direction ⇒ platform speak-only) to an explicit "direction": "both" — i.e. behavior now matches what the helper has always documented. If anyone has been relying on the accidental speak-only behavior, this PR changes what their tap captures. The alternative (documenting "speak" as the default instead) preserves accidental behavior but breaks the documented contract; happy to switch if that's preferred.

Cross-repo note

tap.direction's Literal feeds the port-audit oracle (python_signatures.json in porting-sdk) as an enum<...>; the oracle needs a regen alongside this change (test_validated_closed_sets_declared_as_literal pins the tuple in-repo and is updated here).

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https://claude.ai/code/session_01MgA3KeCEPMKMJVvroZY1wV