HS: ask/answer + prompt/confirm mock (+4 tests)

Wire up the `ask` and `answer` commands end-to-end:

- tokenizer.sx: register `ask` and `answer` as hs-keywords.

- parser.sx: cmd-kw? gains both; parse-cmd dispatches to new
  parse-ask-cmd (emits `(ask MSG)`) and parse-answer-cmd, which
  reads `answer MSG [with YES or NO]`. The with/or pair reads
  yes/no via parse-atom — parse-expr would collapse
  `"Yes" or "No"` into `(or "Yes" "No")` before match-kw "or"
  could fire. The no-`with` form emits `(answer-alert MSG)`.

- compiler.sx: three new cond branches (ask, answer, answer-alert)
  compile to a let that binds __hs-a, sets `the-result` and `it`,
  and returns the value — so `then put it into ...` works.

- runtime.sx: hs-ask / hs-answer / hs-answer-alert call
  window.prompt / confirm / alert via host-call + host-global.

- tests/hs-run-filtered.js: test-name-keyed globalThis.{alert,
  confirm,prompt}; __currentHsTestName is updated before each
  test. Host-set! for innerHTML/textContent now coerces JS
  null → "null" (browser behaviour) so `prompt → null` →
  `put it into #out` renders literal text "null", which the
  fourth test depends on.

Suite hs-upstream-askAnswer: 1/5 -> 5/5.
Smoke 0-195: 166/195 -> 170/195.

plans/hs-conformance-scoreboard.md

@@ -4,10 +4,10 @@ Live tally for `plans/hs-conformance-to-100.md`. Update after every cluster comm
 
 ```
 Baseline:   1213/1496 (81.1%)
-Merged:     1260/1496 (84.2%)   delta +47
+Merged:     1264/1496 (84.5%)   delta +51
 Worktree:   all landed
 Target:     1496/1496 (100.0%)
-Remaining:  ~236 tests
+Remaining:  ~232 tests
 ```
 
 ## Cluster ledger
@@ -53,7 +53,7 @@ Remaining:  ~236 tests
 |---|---------|--------|---|--------|
 | 26 | resize observer mock + `on resize` | done | +3 | 304a52d2 |
 | 27 | intersection observer mock + `on intersection` | done | +3 | 0c31dd27 |
-| 28 | `ask`/`answer` + prompt/confirm mock | pending | (+4 est) | — |
+| 28 | `ask`/`answer` + prompt/confirm mock | done | +4 | SHA-PENDING |
 | 29 | `hyperscript:before:init` / `:after:init` / `:parse-error` | pending | (+4–6 est) | — |
 | 30 | `logAll` config | done | +1 | 64bcefff |
 
@@ -87,7 +87,7 @@ Defer until A–D drain. Estimated ~25 recoverable tests.
 |--------|-----:|--------:|--------:|--------:|--------:|------------:|------:|
 | A      | 12   | 4       | 0       | 0       | 1       | —           | 17    |
 | B      | 5    | 0       | 0       | 1       | 1       | —           | 7     |
-| C      | 3    | 0       | 0       | 2       | 0       | —           | 5     |
+| C      | 4    | 0       | 0       | 1       | 0       | —           | 5     |
 | D      | 0    | 0       | 0       | 5       | 0       | —           | 5     |
 | E      | 0    | 0       | 0       | 0       | 0       | 5           | 5     |
 | F      | —    | —       | —       | ~10     | —       | —           | ~10   |