Add mapbox map-matching

[mattpodwysocki]

⚠️ Temporarily based on #44, not main

Same stacking situation as #44 on #43. This reuses the flattening mechanism
(spec::FLATTENED_SERVICES), ARG_NAME_OVERRIDES, and the
path_segment_for/UNESCAPED_PATH_PARAMS fix #43 introduces, since every
one of these Navigation APIs' profile path parameter hits the same
global-flag collision and needs the same free-form profile. Once #43 and
#44 merge in order, this should be retargeted to main (gh pr edit --base main). Everything below is scoped to what this PR actually adds on top of
#44.

What

mapbox map-matching, the third Navigation-category API with no prior
CLI coverage. Same shape as #43/#44: hand-authored into custom-openapi/
since openapi-specs publishes no spec for it either.

No subcommand: like mapbox directions and mapbox isochrone, this API
has one operation, so there's nothing a second word (the old match)
would disambiguate. Same shape mapbox usage already has.

Snaps a noisy GPS trace to the road network and returns the route it most
likely followed, for driving (with or without live traffic), walking, or
cycling. One or more matched routes (more than one where the trace is
ambiguous enough to split), each with a confidence, plus one tracepoint
per input coordinate (null for one too far from any candidate to match at
all).

Excluded on purpose: POST, for the same reason directions excludes
it. This spec format has no way to express "GET or POST, caller's choice"
for one operationId. The API's own POST exists specifically for a trace
too long for a URL (~8100 bytes), a real gap for a very long trace rather
than a design choice.

Routing profile is free-form here too

Same fix as #43 and #44: an earlier version of this command validated
profile against the four documented values client-side, via a clap enum.
Some OEM accounts have additional profiles that aren't published, so that
validation would have broken this command for exactly the accounts that
most need it. profile is now sent exactly as typed, and reaches the URL
unescaped through UNESCAPED_PATH_PARAMS (("map-matching", "profile")).

Verification

Smoke-tested against production: a three-point San Francisco trace
returned a real match with legs/steps/geometry, including a null
tracepoint for a point deliberately placed too far from the road network to
match, the documented shape for that case, confirmed rather than assumed.
The bare mapbox map-matching command shape itself is also verified (no
subcommand accepted, --schema reflects the new name).

489 tests, cargo fmt --check and cargo clippy --all-targets -- -D warnings both clean.

🤖 Generated with Claude Code