docs: project README, changelog, and M0 marked done

The README leads with the thing that is actually different about this app
rather than burying it: Calendula and Agendula front standards someone else
maintains, and Clockula cannot, because there is no open provider behind a
clock. Saying so plainly is better than implying a thesis the app does not
meet — and the three things that replace it (the AlarmClock contract, IANA
zones, an exportable format) are real commitments, not consolation.

CONTRIBUTING's scope section now names the trade this project will not make:
nothing ships that buys a feature by making an alarm less certain to ring.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L94fydiJC37LtxVusNQBDy

docs/ROADMAP.md

@@ -10,7 +10,10 @@ Status legend: ✅ done · 🚧 in progress · ⬜ not started
 
 ## Current state (one line)
 
-⬜ **Nothing built yet.** The spec is locked (`PLAN.md`); M0 is next.
+✅ **M0 done.** The project builds, installs and shows a themed placeholder;
+floret-kit is wired in as a composite build, the identity is seeded, and the
+full Codeberg-canonical release pipeline is in place. **M1** (the `core-prefs` +
+`core-di` extraction into floret-kit) is next.
 
 ---
 
@@ -42,7 +45,7 @@ Rules that hold across every iteration:
 
 ## v1 milestones
 
-### ⬜ M0 — Skeleton & pipeline
+### ✅ M0 — Skeleton & pipeline
 The project exists, builds, is themed, and ships itself.
 - Gradle project: `settings.gradle.kts`, version catalog copied from Agendula
   (drop `:provider`, add Room + KSP), AGP 9.x conventions, `vcsInfo` off on
@@ -59,6 +62,13 @@ The project exists, builds, is themed, and ships itself.
   `.gitignore`, `docs/README.md` index.
 - **Done when:** it builds, installs, shows a themed placeholder, and CI is green.
 
+  ✅ `assembleDebug`, `lintDebug` and `testDebugUnitTest` all pass;
+  `scripts/check_reproducible_release.sh` reports every invariant holding.
+  Two notes for later: the store listing and `fastlane` changelogs are written
+  but no screenshots exist yet (M11), and `docs/ARCHITECTURE.md` is still
+  unwritten by design — M2 writes it, once there is an architecture to
+  describe.
+
 ### ⬜ M1 — floret-kit: `core-prefs` + `core-di`
 Pay the extraction the kit's roadmap has been waiting for a third app to trigger.
 - In the kit: `core-prefs` (`ThemeMode`, `dynamicColor`, typed DataStore wrapper,