fix(share,r): validate map_name/verbose on master

[davidbudzynski]

Closes #59.

shareData/getData passed raw args to C: "", NA_character_ and R-coerced numerics (via sub() in shmName) reached shm_open and produced only the cryptic * Creating file mapping...ERROR (cf. #40). close(conn) had no on.exit guard, leaking the connection when serialize fails.

• R/call.R: shmName now validates (is.character + length 1 + !is.na + nzchar, NA checked before nzchar since nzchar(NA) is TRUE) then normalizes sub("^/*", "/", .); new internal checkVerbose (is.logical + length 1 + !is.na, message matches house style); also applied to clearData; connections closed via on.exit(close(conn), add = TRUE) (explicit close removed to avoid double-close).
• test-share.R: 9 validation tests (share-0059.001–009) placed before the shm-gated roundtrip so they run even without shm.
• NEWS.md: bug-fix entry.

Verification: all bad inputs now fail fast with clear R errors, valid roundtrip + clearData still TRUE, full tinytest suite green (1418 results). R-only, O(1) checks before O(n) serialize — no hot-path impact.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.27%. Comparing base (99413b6) to head (df60c6f).
⚠️ Report is 67 commits behind head on master.
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Additional details and impacted files

@@            Coverage Diff             @@
##           master      #71      +/-   ##
==========================================
+ Coverage   98.01%   98.27%   +0.26%     
==========================================
  Files          13       13              
  Lines        5083     5105      +22     
==========================================
+ Hits         4982     5017      +35     
+ Misses        101       88      -13     

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