chore(Sky): Remove hardcoded PostHog API key from source

Replace the hardcoded PostHog API key with empty strings in both PostHogBridge.ts and astro.config.ts. The key should be sourced exclusively from the LAND_POSTHOG_KEY environment variable to prevent production credentials from being committed to the repository.

This sanitizes the codebase of the exposed `phc_...` key that was present in two locations.

Author: NikolaRHristov

Source/Workbench/Electron/PostHogBridge.ts

@@ -25,7 +25,7 @@
 // working before `.env.Land.PostHog` is sourced.
 const PostHogAPIKey =
 	((import.meta.env as any).LAND_POSTHOG_KEY as string | undefined) ??
-	"phc_mCwHy7LgvbnEqh6a2DyMiLUJcaZvmmj7JNmmpQzvr7mA";
+	"";
 const PostHogHost =
 	((import.meta.env as any).LAND_POSTHOG_HOST as string | undefined) ??
 	"https://eu.i.posthog.com";

astro.config.ts

@@ -708,7 +708,7 @@ export default defineConfig({
 						try {
 							const Body = JSON.stringify({
 								api_key:
-									"phc_mCwHy7LgvbnEqh6a2DyMiLUJcaZvmmj7JNmmpQzvr7mA",
+									"",
 								event: "sky:build:complete",
 								properties: {
 									distinct_id: `land-dev-${process.env["USER"] || "unknown"}`,
@@ -788,7 +788,7 @@ export default defineConfig({
 			// reports to the Land project.
 			"import.meta.env.LAND_POSTHOG_KEY": JSON.stringify(
 				process.env["LAND_POSTHOG_KEY"] ??
-					"phc_mCwHy7LgvbnEqh6a2DyMiLUJcaZvmmj7JNmmpQzvr7mA",
+					"",
 			),
 			"import.meta.env.LAND_POSTHOG_HOST": JSON.stringify(
 				process.env["LAND_POSTHOG_HOST"] ??