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>

.github/workflows/ci.yml

@@ -7,6 +7,12 @@ on:
     branches: [main]
   pull_request:
     branches: [main]
+  # Manual trigger for the twilio-live job (pre-release validation against
+  # real Twilio credentials). Never runs per-PR — the routine clippy/test
+  # jobs use default features (MockCallControlClient); the live
+  # TwilioCallControlClient is feature-gated behind `twilio-live` + only the
+  # maintainer exercises it before tagging a release (spec §1.2 + plan T6/T10).
+  workflow_dispatch:
 
 env:
   CARGO_TERM_COLOR: always
@@ -80,3 +86,34 @@ jobs:
       - uses: EmbarkStudios/cargo-deny-action@v2
         with:
           command: check
+
+  # The live TwilioCallControlClient is feature-gated behind `twilio-live`
+  # (reqwest + rustls-tls + tracing + serde_json pulled in only when the
+  # feature is on). This job exercises it against REAL Twilio credentials.
+  # It runs ONLY on manual `workflow_dispatch` (never per-PR) — the routine
+  # clippy/test jobs above use default features (MockCallControlClient).
+  # The maintainer triggers this before tagging a release, after setting the
+  # TWILIO_* secrets in the repo settings (spec §1.2 + plan T10 Step 3).
+  twilio-live:
+    name: twilio-live (manual only)
+    runs-on: ubuntu-latest
+    if: github.event_name == 'workflow_dispatch'
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - name: Install libopus (media crate FFI dep)
+        run: apt-get update && apt-get install -y libopus-dev
+      - uses: Swatinem/rust-cache@v2
+      - name: Clippy with twilio-live feature
+        run: cargo clippy --all --all-targets --features=twilio-live -- -D warnings
+      - name: Twilio-live tests (includes ignored live e2e; needs TWILIO_* secrets)
+        env:
+          RUTSTER_TWILIO_ACCOUNT_SID: ${{ secrets.TWILIO_ACCOUNT_SID }}
+          RUTSTER_TWILIO_AUTH_TOKEN: ${{ secrets.TWILIO_AUTH_TOKEN }}
+          RUTSTER_TWILIO_MEDIA_BIND: 0.0.0.0:8081
+          RUTSTER_TWILIO_WEBHOOK_BASE: ${{ secrets.TWILIO_WEBHOOK_BASE }}
+          RUTSTER_TWILIO_TEST_TO: ${{ secrets.TWILIO_TEST_TO }}
+          RUTSTER_TWILIO_TEST_FROM: ${{ secrets.TWILIO_TEST_FROM }}
+        run: cargo test --all --features=twilio-live -- --include-ignored