Thin the app's comments

The same pass the server had, on the Kotlin side: comments restating what
the code says are gone, and the ones recording a measurement, a constraint
or an incident are kept but cut to a few lines each. 6540 comment lines to
5674, and 920 lines off the app.

Two doc comments had drifted onto the item above the one they describe --
`contextAfter`'s onto `sessionWorking` in Events.kt, and `UsageMonitor`'s
equivalent on the server was fixed in the previous commit. Each is back on
its own item, which is the only non-comment line this diff moves.

The comments are reflowed to the column limit at their own indentation:
several were written wide, and ktfmt re-wrapped them into lines holding a
single orphan word. `/tmp` script, not kept -- ktfmt is idempotent over the
result, which is the check.

Left alone deliberately: this codebase's remaining comment density is high
because the comments carry things the code cannot say -- what a null means,
what a number was measured against, which bug a guard exists for. Of the
238 one-line doc comments in the app, five were pure restatement of the
name and were removed; the rest each say something the signature does not.

ktfmtFormat, compileDebugKotlin, lintDebug and testDebugUnitTest pass;
cargo test (127), clippy --all-targets and fmt still clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/androidApp/src/main/kotlin/com/example/aiapp/Chevron.kt

@@ -27,13 +27,10 @@ enum class Pointing {
  *
  * One composable for all four directions rather than one per axis that differ by which coordinate
  * gets the minus sign -- the copies would drift, and the drift would be a bug in exactly one
- * direction. The shape is written once in its own coordinates, where x runs across the opening and
- * y runs from the open side to the tip, and [Pointing] is only a table of how those two map onto
- * the box.
+ * direction. The shape is written once in its own coordinates, and [Pointing] is only a table of
+ * how those map onto the box.
  *
- * It draws no label of its own, so every caller owes it a `contentDescription`: this is the whole
- * of what assistive technology has to go on, and it is also the answer to "what was that arrow for"
- * six months from now.
+ * It draws no label of its own, so every caller owes it a `contentDescription`.
  */
 @Composable
 fun Chevron(