feat: add ?dst and ?src URL params for address-based deep-linking

[DennisOSRM]

Summary

Closes #337

Allows third-party sites to deep-link into the OSRM frontend with a pre-set destination (and optionally an origin) by address string — no coordinate lookup required.

New URL parameters

Param	Description
?dst=<address>	Destination address, geocoded on page load
?src=<address>	Origin address, geocoded on page load (optional)

Examples:

https://map.project-osrm.org/?dst=Berlin
https://map.project-osrm.org/?src=Paris&dst=Berlin

How it works

1. links.js parses ?src/?dst into originAddress/destinationAddress in the options object
2. On page load, index.js checks for these values; if present and no loc= coordinate waypoints exist, it geocodes the addresses via Nominatim and calls lrmControl.setWaypoints()
3. The existing state machinery then replaces the URL with loc= coordinate params — so the one-time address params are not persisted in the URL after the first load

?loc= coordinate params take priority: if waypoints were already set via loc=, the address params are ignored (existing sessions are unaffected).

Changes

• src/links.js — parse q.src/q.dst in parseLink(); not included in formatLink()
• src/index.js — geocode address params after LRM init and set waypoints
• test/links.test.js — 10 new unit tests (68 total, all passing)

[Copilot]

Pull request overview

Adds support for one-time address-based deep-linking into the OSRM frontend via ?dst=<address> and optional ?src=<address>, geocoding them on initial page load (only when no loc= waypoint coordinates are present) and then letting the existing state/URL machinery take over.

Changes:

• Parse src/dst query params into originAddress/destinationAddress in src/links.js.
• In src/index.js, geocode originAddress/destinationAddress after LRM initialization and call lrmControl.setWaypoints() when no coordinate waypoints exist.
• Add Jest unit tests verifying parsing behavior and ensuring format() does not serialize src/dst.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/links.test.js	Adds unit tests for parsing src/dst and ensuring they aren’t serialized back into URLs.
src/links.js	Extends link parsing to capture originAddress/destinationAddress from query params.
src/index.js	Applies parsed address params by geocoding and setting waypoints when loc= isn’t provided.

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[Copilot]

qs.parse can return arrays/objects for repeated or nested query params (e.g. ?dst=a&dst=b => q.dst is an array). Assigning q.src/q.dst directly means originAddress/destinationAddress may be non-strings, which can later break geocoding (expects a string). Consider normalizing these to a single string (e.g., first element) or explicitly coercing/validating type before storing them in parsedValues.