feat(freelancer-edit): add the missing GitHub link field

The edit form carried LinkedIn/Upwork/Fiverr but not GitHub, though the
application form, the webhook and the card renderer already do. Add a
fourth optional link field mirroring the other three, under the live wire
key verbatim (lower-case github; never normalised), pre-filled from the
record and added to the save loop with the same rules: a key is written
only when the input has a value, an empty optional field never invents ""
on a record that never had one, and a link the owner cleared sends "".
No new URL check — the card's isLink() stays the only url predicate.

freelancer-edit/index.html

@@ -183,11 +183,12 @@
           description: ["description", "Description"],
           Country: ["Country", "country"],
           OCA_link: ["OCA_link", "oca_link"],
-          // The three profile links. The primary name is the LIVE wire key, casing and all —
-          // "Linkedin", "upwork", "fiverr" are deliberately mixed and must never be normalised
-          // (a normalised key is the silent-drop class that ate odoo_versions). A same-word
-          // casing variant is the identical fallback, the way Name/name already works.
-          Linkedin: ["Linkedin", "linkedin"], upwork: ["upwork", "Upwork"], fiverr: ["fiverr", "Fiverr"],
+          // The four profile links. The primary name is the LIVE wire key, casing and all —
+          // "Linkedin", "github", "upwork", "fiverr" are deliberately mixed and must never be
+          // normalised (a normalised key is the silent-drop class that ate odoo_versions). A
+          // same-word casing variant is the identical fallback, the way Name/name already works;
+          // "github" is lower-case on the wire, so it is read exactly as it is, with no variant.
+          Linkedin: ["Linkedin", "linkedin"], github: ["github"], upwork: ["upwork", "Upwork"], fiverr: ["fiverr", "Fiverr"],
           functional: ["functional"], system: ["system"], modules: ["modules"],
           integration: ["integration"], ai: ["ai"],
           english: ["english"], german: ["german"], spanish: ["spanish"]
@@ -560,12 +561,14 @@
           form.appendChild(textField("edOcaLink", "OCA member profile link", readField(record, "OCA_link"),
             0, "Your OCA profile URL, if you have one: https://apps.odoo-community.org/community/…"));
 
-          // The three profile links — parity with the application form. Keys are the LIVE wire
-          // keys verbatim ("Linkedin" capital L, "upwork" and "fiverr" lower) and the labels and
-          // placeholders are the application form's own. Each is optional and pre-filled from the
-          // record.
+          // The four profile links — parity with the application form. Keys are the LIVE wire
+          // keys verbatim ("Linkedin" capital L; "github", "upwork" and "fiverr" lower) and the
+          // labels and placeholders are the application form's own. Each is optional and
+          // pre-filled from the record.
           form.appendChild(linkField("edLinkedin", "Linkedin", "LinkedIn URL",
             readField(record, "Linkedin"), "https://www.linkedin.com/in/…"));
+          form.appendChild(linkField("edGithub", "github", "GitHub URL",
+            readField(record, "github"), "https://github.com/…"));
           form.appendChild(linkField("edUpwork", "upwork", "Upwork URL",
             readField(record, "upwork"), "https://www.upwork.com/freelancers/…"));
           form.appendChild(linkField("edFiverr", "fiverr", "Fiverr URL",
@@ -669,12 +672,12 @@
             payload.OCA_link = document.getElementById("edOcaLink").value.trim();
             C.focusAxes.forEach(function (axis) { payload[axis] = num(document.getElementById("ed-" + axis).value, 0); });
             C.langs.forEach(function (pair) { payload[pair[0]] = num(document.getElementById("ed-" + pair[0]).value, 0); });
-            // The three links, read from their inputs. Only a key we actually have a value for is
+            // The four links, read from their inputs. Only a key we actually have a value for is
             // touched: an empty optional field must NOT invent an empty string on a record that
             // never had one — the record's own value (null, or absent) is already in the payload
             // and is left as it is. A link the record DID carry and the owner cleared is a
             // deliberate clear and sends "".
-            [["edLinkedin", "Linkedin"], ["edUpwork", "upwork"], ["edFiverr", "fiverr"]].forEach(function (pair) {
+            [["edLinkedin", "Linkedin"], ["edGithub", "github"], ["edUpwork", "upwork"], ["edFiverr", "fiverr"]].forEach(function (pair) {
               var input = document.getElementById(pair[0]);
               if (!input) return;
               var v = input.value.trim();