perf(voice): skip strip_raw_urls in for_voice when no URL marker

[jony376]

Summary

Skips the allocating strip_raw_urls scan in for_voice when no raw URL marker is present, and elides the redundant normalize_whitespace pass on the URL-stripped path. Most spoken replies avoid one to two buffer allocations per call while preserving byte-identical TTS text.

Fixes #645

Changes

• needs_raw_url_strip marker gate over http://, https://, and www.; strip_raw_urls runs only when a marker is present.
• No-URL path keeps normalize_whitespace; URL-stripped path skips it because split_whitespace already collapses whitespace.
• Removed the redundant initial text.to_string() before strip_markdown.
• Added for_voice_corpus_regression and a clean-no-url voice_format_bench case.

Real Behavior Proof

• I have built and run the affected code locally (or noted why I could not).
• I have verified the change end-to-end on Jetson hardware.
• I have NOT verified on Jetson hardware, and I explain the equivalent verification path or validation gap below.

Tested profile / hardware (check all that apply):

• jetson
• raspberry_pi
• portable_sbc
• laptop
• mac
• CI-only / docs-only
• Not run locally

What I ran

No local Rust toolchain on this Windows dev machine (cargo not on PATH). Pushed branch and relied on upstream CI (cargo fmt, cargo clippy -D warnings, cargo test --features voice) for correctness proof. The for_voice_corpus_regression test and the 16 existing for_voice integration tests guard byte-identical output.

What I observed

Awaiting CI on push. Prior merged perf PRs (#608, #643) validated the CI-only path on this repo.

Test plan

• cargo test -p genie-core --features voice for_voice
• Optional Jetson: cargo test -p genie-core --features voice --release --ignored --nocapture bench_for_voice

Notes for reviewers

Complements #483 (single-pass helpers inside each stage). This PR targets the outer pipeline: skipping whole stages on the common no-URL path. The marker set is a conservative superset of the strip_raw_urls prefixes.

[matedev01]

Thanks — but this is voice-runtime-internal perf, out of the M2 scope (portable providers + channel boundaries). Closing as out-of-scope.