ci(trunk): twilio-live manual-trigger job + seam-gate verification + doc-link fixes (slice-5 T10)

The routine CI gate stays feature-default-off: MockCallControlClient is the
per-PR test surface. A new twilio-live job runs ONLY on manual
workflow_dispatch (maintainer triggers pre-release) -- it exercises clippy
--features=twilio-live + the live TwilioCallControlClient tests against real
Twilio credentials (TWILIO_* secrets). Never runs per-PR.

Seam gate verified UNCHANGED: loop_driver.rs (744bf314...) + rtc_session.rs
(f47d63b9...) blob hashes match the slice-4 Task 10 pins exactly -- the trunk
leg's tick lives entirely in rutster-trunk/src/loop_driver.rs (a separate file
in a separate crate), so the media-crate seam files stay byte-identical.

cargo deny: reqwest (rustls-tls) + base64 + async-trait introduce ZERO new
duplicate dep versions (verified via `cargo tree -d` with vs without
--features=twilio-live: identical duplicate sets -- the existing skip list in
deny.toml remains sufficient). Local cargo-deny 0.18.3 cannot parse the
`-or-later` SPDX form + CVSS 4.0 advisory entries (pre-existing limitation
documented in deny.toml; CI's cargo-deny-action@v2 bundles 0.19.x which handles
both) -- CI is the authoritative deny gate.

Two rustdoc intra-doc-link warnings in my code fixed (mock.rs private-item
link -> plain inline code; lib.rs redundant explicit link target simplified).
Two pre-existing rustdoc warnings remain in rutster-tap/protocol.rs +
rutster/tap_engine.rs (out of scope -- pre-existing from slices 2-3, not
introduced by slice-5).

T10 of slice-5. This is the final task on the dev-b chain (T2 + T6 + T9 + T10
all landed).

Signed-off-by: Aaron D. Lee <himself@adlee.work>

crates/rutster-trunk/src/lib.rs

@@ -10,7 +10,7 @@
 //!
 //! ## Spearhead step 5 — what's here vs what's deferred
 //!
-//! The provider call-control seam ([`provider`](crate::provider)) lands in T2: the
+//! The provider call-control seam ([`provider`]) lands in T2: the
 //! `CallControlClient` trait, `MockCallControlClient`, and `TwilioCredentials` (with
 //! redacted `Debug`). The live `TwilioCallControlClient` (T6) is feature-gated behind
 //! `twilio-live`. The WSS ingress (`g711`, `twilio_media_streams`, `session`,

crates/rutster-trunk/src/provider/mock.rs

@@ -21,7 +21,7 @@
 //! *test double*, a poisoned mutex means a previous test assertion failed; the
 //! right move is to recover the inner value (`.into_inner()`) rather than
 //! propagate the poison (which would cascade one test failure into every
-//! subsequent test). [`lock_or_recover`] does this idiomatically — and avoids
+//! subsequent test). `lock_or_recover` does this idiomatically — and avoids
 //! the `unwrap()`/`expect()` that AGENTS.md's hot-path rule forbids in library
 //! code (the mock is library code, not `#[cfg(test)]`, because T7/T8 integration
 //! tests in `tests/` import it).