New optimizations to detect early when queries return no rows due to

tables being empty.  This includes the EXISTS-to-JOIN optimization that
tries to transform EXISTS constraints into additional terms of the FROM
clause.

FossilOrigin-Name: e33da6d5dc964db817d1bc63c9083aecd93d49ee14d5198600b47eaf7c5b9331

diff --cc manifest
index 53a33eba01698195a4a36f4667d28d3579c66eef,ff1e16970164caa1bdb62a5100c5576be3c5c4e6..acdcb2527cd3d92201224d114370cb68481f15cb
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Fix\sa\sproblem\swith\sthe\sfix\sin\s[5cb8e342e1].
- D 2025-07-08T19:02:26.486
 -C Enable\sthe\sEXISTS-to-JOIN\soptimization\sif\sthe\souter\squery\shas\sno\nFROM\sclause.
 -D 2025-07-08T17:28:09.030
++C New\soptimizations\sto\sdetect\searly\swhen\squeries\sreturn\sno\srows\sdue\sto\ntables\sbeing\sempty.\s\sThis\sincludes\sthe\sEXISTS-to-JOIN\soptimization\sthat\ntries\sto\stransform\sEXISTS\sconstraints\sinto\sadditional\sterms\sof\sthe\sFROM\nclause.
++D 2025-07-08T19:53:36.480
  F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@@ -2208,8 -2211,8 +2211,9 @@@ F tool/version-info.c 3b36468a90faf1bbd
  F tool/warnings-clang.sh bbf6a1e685e534c92ec2bfba5b1745f34fb6f0bc2a362850723a9ee87c1b31a7
  F tool/warnings.sh 1ad0169b022b280bcaaf94a7fa231591be96b514230ab5c98fbf15cd7df842dd
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
- P 5cb8e342e1d33a0fd04fd022900eeada46a2ee23f15c6abca1b37633e77429d6
- R 2f815a7ddd919cbdb9dea42abcf9e107
- U dan
- Z 1f7246259d459232db167600e0b56367
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 -R e35575e41e9bd119ef19709aeaa4c684
++P 043ff54fb746c54bc6cfa6aa8c8a32c876c09d36163125916ad01024b98d447b 1b9b124f9a35ebd1ac4ea70ef1ee08a4c82c11da690d4164f6b785a6fd9730d9
++R f2382be8a4dd59640ba7d3e608aa0208
++T +closed 1b9b124f9a35ebd1ac4ea70ef1ee08a4c82c11da690d4164f6b785a6fd9730d9
+ U drh
 -Z 4da98ddcb106ab62869cc3825500f67f
++Z 2faf96645b8f6e620da8ad84b2b3ac57
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index 10ef81e7bd17877f7b1759d8187563f9f14f782e,384e800b522872a6fcc4780d40cf2ec48b72aa4c..156cff42a4281892bb6165f91429b7516e9f290d
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 043ff54fb746c54bc6cfa6aa8c8a32c876c09d36163125916ad01024b98d447b
 -1b9b124f9a35ebd1ac4ea70ef1ee08a4c82c11da690d4164f6b785a6fd9730d9
++e33da6d5dc964db817d1bc63c9083aecd93d49ee14d5198600b47eaf7c5b9331