fix: give the phone Chat composer full touch targets

[lukemaj]

Caution

Frozen stacked predecessor candidate. Do not merge this PR. This head 60430bff5740d6fe3c07e2b51816152dd7219f8b is stacked on stale PR #138. Its deterministic and Browser proof is valid only for that exact predecessor stack and must not be transferred to a corrected train. After PR #136 exact-head live and human disposition, rebuild #137 first, then rebuild #139 and rerun exact-candidate acceptance.

Tracks #139. This frozen stacked PR does not close the issue.

Summary

• give the phone Chat textarea the existing 44px --touch-min height
• give the phone Send control the existing 44x44 touch target
• keep the desktop composer at its existing compact 40px density
• leave the shared button primitive and unrelated spacing unchanged

This PR is stacked on #138 (fix/137-selected-bot-panel-overflow-v0.15.1) because #139 was found during exact-build acceptance of that candidate.

Deterministic proof

• red: focused test failed before production with the new composer contract imports missing
• focused pwa/test/chat-interactions.test.ts: 13/13
• affected PWA preservation: 125/125 across 19 suites
• daemon and PWA typechecks: pass
• production PWA build: pass, 2,323 modules
• one serialized full suite: 841/841 across 84 suites, with 0 failed, cancelled, skipped, or todo
• versionctl doctor and exact clean-commit release-check: pass for v0.15.2 at 60430bff5740d6fe3c07e2b51816152dd7219f8b

Exact-build Browser proof

Fresh isolated production build and private loopback Home:

• phone 390x844: Send 44x44, textarea 44px high, document 390/390, scrollX=0
• desktop 1280x720: Send 40x40, textarea 40px high, document 1280/1280, scrollX=0
• Send remains icon-only with accessible name Send; disabled truth preserved
• composer pill visually intact at both breakpoints
• application warning/error console: []
• isolated tab count restored from 0/0 to 0/0, viewport reset, server stopped, port released, private Home/build removed from the live boundary

Scope

Exactly six files: CHANGELOG.md, VERSION, package.json, pwa/src/components/Messenger.tsx, pwa/src/lib/chat-interactions.ts, and pwa/test/chat-interactions.test.ts.

No Screen, PinchTab, ACP, Harness, daemon, auth, shared button primitive, merge, tag, release, deployment, or installation change.

[lukemaj]

Dispatcher train-order warning. Do not merge this PR yet.

GitHub currently records this PR with:

• base fix/137-selected-bot-panel-overflow-v0.15.1 at 2bf9e07
• head fix/139-phone-composer-touch-v0.15.2 at 60430bf
• OPEN, non-draft, MERGEABLE, CLEAN
• zero configured checks

This PR is stacked on #138, whose base is still the pre-correction #116 SHA ce091ba.

The live evidence for exact branch candidate 60430bf remains truthful as branch-scoped evidence. It is not proof for the corrected combined train rooted at 47923fd.

Merging #140 now would advance the branch used as PR #138's head and cascade a material change into that open PR. Wait for #116 human disposition, then re-anchor the corrected #137/#139 successor deliberately.

No retarget, rewrite, head update, or merge is authorized by this comment.