fix(dispatch-gates): mask # comments on shell-kind sources, so a shell target's inherited population is not prose

`extractWatchHints` masked its source with `maskedModuleBody`, which understands
every comment syntax JavaScript has. `PROGRAM_TEXT_TARGET` admits a third file
kind, `.sh`, whose prose is none of them: every path a `#` comment mentioned came
back as a watch hint, because the JS-shaped literal regex reads a backticked path
as a template literal and a double-quoted one as a string.

The mask is kind-scoped and composes ONTO the JS mask rather than replacing it,
so the shell hint set is a subset of today's by construction. Quote state is
line-scoped: a cross-line scanner desyncs on command substitution and on a `<<<`
here-string, and one unbalanced quote then disables the mask for the rest of the
file — the fabricating direction. The residue is a bounded over-mask.

Measured over the 27 tracked `.sh` files: 37 hints as spelled, 8 after the mask.
Tree-wide over 6,361 scanned files: 11 changed, 11 shrank, 0 grew. The live
derivation is byte-identical, because no family-to-`.sh` population edge exists
yet.

Claude-Session: https://claude.ai/code/session_012GKcPZbMoGq7WPzKLfRBTU
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

scripts/pm/dispatch-gates.mjs

@@ -516,7 +516,10 @@ const maskedModuleBody = memoiseMask((source) => maskSelfTests(maskedComments(so
  * `.sh` files: 37 hints as spelled, 8 once `#` comments are masked, and 8 of the
  * 16 files that spell any hint at all had a population that was 100% prose.
  * `scripts/bump-objectui.sh` was the sharpest — 7 hints, every one of them
- * inside a `#` comment or an `echo` line.
+ * inside a `#` comment or an `echo` line. Re-taken unchanged after merging
+ * `5e53d73d`; the self-test asserts the DIRECTION rather than these numbers,
+ * because a reading belongs to a named commit and this one moves whenever a
+ * shell script gains or loses a comment.
  *
  * That is the one direction this file refuses everywhere else, stated twice next
  * door: `spawnedProgramTargets` takes a missing lead over a fabricated one, and