Build: org.thisisthepy coordinates, io.github.thisisthepy app IDs (#95) - #333

Closes #95 (all of (a) to (d), approved).

• (a) Maven group io.github.thisisthepy -> org.thisisthepy: root allprojects, the library's publication, KSP, compose, Gradle plugin. The plugin's baked processor and wasm-runtime coordinates follow; PublishedVersionTest is updated.
• (b) Plugin ID: org.thisisthepy.python.multiplatform.bindings (gradlePlugin block, every fixture, sample, settings, wasm.yml text).
• (c) Sample app identity -> io.github.thisisthepy.python.multiplatform.demo: Android namespace and applicationId, desktop packageName, iOS PRODUCT_BUNDLE_IDENTIFIER (2), and the bundle ID in docs/platforms/ios-app-bundle.md. sample code uses no R or BuildConfig, so the namespace change is safe. :sample:assembleDebug passes. Code packages (mainClass, excludePackages, org.thisisthepy.python.multiplatform.demo.*) are unchanged.
• (d) Generated fragment names derive from group and path: Fragment_io_github_thisisthepy_* -> Fragment_org_thisisthepy_*. Discovery scans the whole package, so behaviour is unchanged. Recorded in the new SPEC L-0 and in docs/design/upcall.md. The pinning tests (WiringTest, GeneratedTableTest, CommonInstallTest, GeneratedAndroidTableTest) are updated.
• Not changed:
  • docs/design/ecosystem.md:692, another project's historical package.
  • The GraalVM verification note's recorded log line, a past run's output.
  • docs/archive.
• Grep: no io.github.thisisthepy library coordinate or plugin ID remains outside those.
• Tests: plugin 351/351, ksp app 80/80, artifact 50/50, compose 129/129, ksp android unit 8/8, sample assembleDebug.
• Publishing: verified into a repo-local Maven directory, which shows only org/thisisthepy/... A full publishAllToMavenLocal follows after merge.
• Other repositories were not touched. toolchain has 15 references (listed in the leader report) for its owner, once the new coordinates are published.