feat: add About well to settings with build info and debug easter egg (#145)

## Summary

Add a new well at the bottom of the settings view displaying application info (license, author, version, build date, git commit hash linked to Gitea), and an easter egg that reveals a debug mode toggle after clicking the version number 10 times.

## Changes

- **`src/popup/index.html`**: Added About well with license, author, version, build date, and linked commit hash. Added hidden debug well with debug mode toggle.
- **`src/popup/views/settings.js`**: Populate About well from build-time constants. Implement version click counter (10 clicks reveals debug well). Wire up debug mode toggle to state and runtime logger.
- **`src/shared/buildInfo.js`** (new): Module exporting build-time constants (`BUILD_VERSION`, `BUILD_LICENSE`, `BUILD_AUTHOR`, `BUILD_COMMIT`, `BUILD_DATE`, `GITEA_COMMIT_URL`) injected by esbuild define.
- **`build.js`**: Read git commit hash (short + full) and version from package.json, pass as esbuild `define` constants. Also reads `GIT_COMMIT_SHORT`/`GIT_COMMIT_FULL` env vars for Docker builds.
- **`Dockerfile`**: Accept `GIT_COMMIT_SHORT` and `GIT_COMMIT_FULL` build args, set as env vars for the build step.
- **`Makefile`**: Pass git commit hashes as Docker build args.
- **`src/shared/state.js`**: Add `debugMode` boolean to state (persisted).
- **`src/shared/log.js`**: Add runtime debug flag that supplements the compile-time `DEBUG` constant. Debug mode toggle updates this flag immediately.

closes #144

Co-authored-by: clawbot <clawbot@noreply.git.eeqj.de>
Co-authored-by: clawbot <clawbot@sneak.cloud>
Co-authored-by: user <user@Mac.lan guest wan>
Co-authored-by: clawbot <clawbot@eeqj.de>
Co-authored-by: sneak <sneak@sneak.berlin>
Reviewed-on: #145
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>

src/shared/log.js

@@ -1,12 +1,27 @@
 // Leveled logger. Outputs to console with [AutistMask] prefix.
-// Level is DEBUG when the DEBUG constant is true, INFO otherwise.
+// Level is DEBUG when the compile-time DEBUG constant is true or the runtime
+// debugMode state flag is enabled.  The runtime flag is checked lazily so it
+// responds immediately when toggled in settings.
 
 const { DEBUG } = require("./constants");
 
 const LEVELS = { debug: 0, info: 1, warn: 2, error: 3 };
-const threshold = DEBUG ? LEVELS.debug : LEVELS.info;
+
+// Runtime debug mode flag — set by settings.js when the user toggles debug
+// mode via the easter egg.  Kept here as a simple mutable reference so it can
+// be updated without circular dependency issues with state.js.
+let _runtimeDebug = false;
+
+function setRuntimeDebug(enabled) {
+    _runtimeDebug = enabled;
+}
+
+function isDebug() {
+    return DEBUG || _runtimeDebug;
+}
 
 function emit(level, method, args) {
+    const threshold = isDebug() ? LEVELS.debug : LEVELS.info;
     if (LEVELS[level] >= threshold) {
         console[method]("[AutistMask]", ...args);
     }
@@ -37,4 +52,4 @@ async function debugFetch(url, opts) {
     return resp;
 }
 
-module.exports = { log, debugFetch };
+module.exports = { log, debugFetch, setRuntimeDebug, isDebug };