Docs(fix): Complete wrapper first-use examples

[tony]

Kotlin and Scala first-use examples currently depend on configuration supplied by the documentation harness, and Scala install blocks contain a literal <version>. Readers can now copy complete build files and programs that select a private socket, create tmux objects, and stop their owned server.

The documentation tests compile and invoke those entry points without lending them imports or fixture variables. Scala install examples use the released 0.0.1-alpha.17, and the install gate rejects placeholder versions. The Kotlin guide explains the public DSL without draft-history or contributor-only narrative; its previous heading anchor is preserved.

Validation

• ./gradlew :libtmux-mcp:test check --no-daemon --max-workers=2 --no-build-cache passed in 2m 52s with JDK 25, tmux 3.7c, and Bash startup files disabled. Kotlin: 62 tests; docs: 142 tests; MCP: 384 tests, one existing skip.
• Complete programs copied verbatim into separate Gradle and sbt consumer projects ran against Maven Central 0.0.1-alpha.17 on tmux 3.2a and 3.7c.
• Removing the Kotlin coroutine import or Scala configuration binding fails compilation. Wrong runtime assertions in either program and a restored <version> each fail the relevant test. Original source bytes were restored afterward.
• Independent review found no remaining issues after the complete-program isolation fix.

The account's normal Bash startup reproduces an existing MCP pending-input assertion failure; /bin/sh exposes two CLI launcher assertions. All three pass together with bash --noprofile --norc, which is also the environment used for the successful full check. No product code or test assertions were changed to address those environment failures.