refactor(tools): fold research tools into :infrastructure:tools (drop new module)

The research feature is "no new architecture" (spec §1) — composition of existing
mechanisms. The only genuinely new code is the two web tools + the HTML→markdown
extractor (spec marks them "(new)"), and those belong with ShellTool/FileReadTool
in :infrastructure:tools, not in a separate module.

Moves extract/ + web/ from the short-lived :infrastructure:research module into
:infrastructure:tools (packages com.correx.infrastructure.tools.{extract,web}); adds
jsoup + ktor-client there; removes the module from settings.gradle. No behaviour change
— 44 tests green.

infrastructure/tools/build.gradle

@@ -4,6 +4,10 @@ plugins {
     id 'org.jetbrains.kotlin.plugin.serialization'
 }
 
+ext {
+    ktor_version = '3.0.3'
+}
+
 dependencies {
     implementation project(":core:tools")
     implementation project(":core:events")
@@ -12,6 +16,13 @@ dependencies {
     implementation project(":infrastructure:tools:filesystem")
     implementation project(":core:artifacts")
     implementation project(":core:artifacts-store")
+
+    // Web research tools (web_search, web_fetch) + deterministic HTML→markdown extraction.
+    implementation 'org.jsoup:jsoup:1.20.1'
+    implementation "io.ktor:ktor-client-core:$ktor_version"
+    implementation "io.ktor:ktor-client-cio:$ktor_version"
+
+    testImplementation "io.ktor:ktor-client-mock:$ktor_version"
 }
 
 tasks.named("koverVerify").configure { enabled = false }