docs: per-module READMEs (run vs library) + root navigation hub

Every subproject now has README.md:
- 3 runnable modules (:standalone, :agentik-cli, :agentik-tui):
  quickstart, env table, parameters, known limits
- 11 library modules: what it is, which problem solves, how to
  wire it in, where versions live

Root README.md is the navigation hub (Quickstart, Modules table,
publish + CI/CD notes).

Also: ci.yml prunes the :memory-vector -x excludes now that
text-embedding-kmp artifacts are published to caffeine.

518 tests green.

Verified publish pipeline: :proto:publish to caffeine produces
pom.module + per-target klibs + sources for all 9 KMP targets.

🤖 Generated with [opencode]

build.gradle.kts

@@ -50,9 +50,9 @@ val moduleDescriptions: Map<String, String> = mapOf(
     "agent-toolsets" to "agentik :agent-toolsets — реестр инструментов + диспетчер тулов (enable_toolset/disable_toolset); переиспользуемое ядро.",
     "agentik-cli" to "agentik :agentik-cli — JVM CLI-клиент (JLine) к /agentik: REPL + slash-команды + стрим SSE.",
     "agentik-tui" to "agentik :agentik-tui — Compose-for-Mosaic TUI-клиент (desktop, без iOS) с клавиатурной навигацией без ':'-префиксов.",
-    "standalone" to "agentik :standalone — single-jar HTTP-сервер со всеми транспортами (AG-UI/A2A/:proto), SQLite, памятью, скилами и SOUL.",
-)
-rootProject.extra.set("moduleDescriptions", moduleDescriptions)
+"standalone" to "agentik :standalone — single-jar HTTP-сервер со всеми транспортами (AG-UI/A2A/:proto), SQLite, памятью, скилами и SOUL.",
+    )
+    rootProject.extra.set("moduleDescriptions", moduleDescriptions)
 
 subprojects {
     group = rootProject.group