half-past hours parse as the hour being entered (V-538)

Russian names a half hour by the hour it is entering, in the genitive, so
"половина восьмого" is 07:30 and never 08:30. Neither date parser read that
shape, so the reminder parsed to nothing.

rewriteHalfPast runs in front of the token pass in SpellOutDigits, so the
python parser and the stub both see "в 7:30". It also reads the contracted
"полвосьмого" and the quarter-to shape "без четверти восемь", which counts
from a cardinal and is 07:45. Minus one is in one place, clockHourBefore, with
twelve rather than zero before one.

Ordinals eleven and twelve added to the lexicon, because a clock reaches them.
Minutes a spoken clock does not use are left alone: a guess here is a missed
dose.

Classifier + onnx over the routing fixture 58/82 to 62/87, three new cases,
none regressed. Python dateparser is not installed on this host, so only the
stub was measured. See docs/evals/2026-08-05-half-past-hours.md.

docs/evals/2026-08-05-half-past-hours.md

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+# Half-past and quarter-to hours, 2026-08-05
+
+Vikunja V-538. `rewriteHalfPast` in `internal/router/halfpast.go`, run in front of
+the token pass inside `SpellOutDigits`, so both date parsers see digits.
+
+## What the shapes are
+
+Russian names a half hour by the hour being ENTERED, in the genitive. "половина
+восьмого" is 07:30. "без четверти восемь" counts the other way, from a cardinal,
+and is 07:45. Both are minus one from the word in the sentence, and the arithmetic
+lives in one function, `clockHourBefore`.
+
+## Result
+
+| | before | after |
+|---|---|---|
+| classifier + onnx over the routing fixture | 58/82 (70.7%) | 62/87 (71.3%) |
+| new fixture cases passing | — | 2 of 3 |
+| stub parser reads a half hour | no | yes |
+
+The three new cases are ru-rem-008, ru-rem-009 and ru-rem-010. No existing case
+regressed and no new clarify appeared.
+
+ru-rem-009, "разбуди меня полвосьмого", still misses the intent. Its two siblings
+without a half hour miss it the same way. ru-rem-005 "разбуди меня в 6:30" routes
+to `fact`, and en-rem-002 "wake me at 6:15" does too. So the miss is the "разбуди"
+phrasing against the classifier, not the half hour. The time slot now fills.
+
+## Not measured here
+
+Python dateparser. It is not installed on this host, so only the stub was run.
+The rewrite emits "в 7:30 вечера". The script's own qualifier rewrite turns that
+trailing "вечера" into "pm", which is the shape it already reads for a whole hour.
+Judge it on the box.
+
+The LLM arm. No llama-server in this run, so the cascade number is the classifier
+floor.
+
+## Left out on purpose
+
+Minutes a spoken clock does not use. "без семи восемь" is not rewritten, because
+nobody says it and a guess in this shape is a missed dose. The parsers fail on it
+as they did before.