Improved rounding of double→text conversions for rounding digits

of 17.  Add the new sqlite3_db_config(), SQLITE_DBCONFIG_FP_DIGITS,
to specify the number of significant digits to preserve on conversions.

FossilOrigin-Name: 78c12b4f6ae869c3ea5e368c97b45991442bdd2d3a60935f1e6fc02a8e01cd41

diff --cc manifest
index 30469cdd112f4c2390069f36bd668cc1a135a156,2bddd7d3ad8eca5d162e84b0950e53bd568394f7..3aa96e6b9d1f71967f3e4f8e2d1d0f6a5da9621b
--- 1/manifest
--- 2/manifest
+++ b/manifest
@@@ -1,5 -1,5 +1,5 @@@
- C Inconsequential\schanges\sto\sfloating-point\sconversion,\samounting\sto\smere\ncode\scleanup\sto\said\scomprehension.
- D 2026-02-20T20:43:25.912
 -C New\ssqlite3_db_config(SQLITE_DBCONFIG_FP_DIGITS)\sthat\slet's\sthe\sapplication\nspecify\sthe\snumber\sof\ssignificant\sdigits\sthat\sdouble→text\sconversions\nwill\sattempt\sto\spreserve.
 -D 2026-02-21T19:26:58.856
++C Improved\srounding\sof\sdouble→text\sconversions\sfor\srounding\sdigits\nof\s17.\s\sAdd\sthe\snew\ssqlite3_db_config(),\sSQLITE_DBCONFIG_FP_DIGITS,\nto\sspecify\sthe\snumber\sof\ssignificant\sdigits\sto\spreserve\son\sconversions.
++D 2026-02-21T20:03:47.616
  F .fossil-settings/binary-glob 61195414528fb3ea9693577e1980230d78a1f8b0a54c78cf1b9b24d0a409ed6a x
  F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
  F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
@@@ -2195,8 -2195,8 +2195,9 @@@ F tool/warnings-clang.sh bbf6a1e685e534
  F tool/warnings.sh d924598cf2f55a4ecbc2aeb055c10bd5f48114793e7ba25f9585435da29e7e98
  F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
  F tool/winmain.c 00c8fb88e365c9017db14c73d3c78af62194d9644feaf60e220ab0f411f3604c
- P cb24edf1afc3f9083a4963c5fe232933eccc7c0cb8872aa5fcd336d226b885ef
- R 5dc7d1cf9df5b4fd3583425b84bcab00
 -P 3033fe97b14ba0531278d4aa444bc5340e044b87a72b3a4341032ddee442000f
++P 6d9c29123b6b143b0f7c8f5d018f170c72edfc5b1a4d67edd45e5552def2af6c 3f16985dcc47a366b54164c5024f920a79dddd76faeac5e36b4770732ed72c0a
+ R 4d154d27dd2b7e6c72267982eae3c18d
++T +closed 3f16985dcc47a366b54164c5024f920a79dddd76faeac5e36b4770732ed72c0a
  U drh
- Z a28f337e825428b6e4dfea35f10cb54e
 -Z 47c16a6580f94070b6e59ea57711afd7
++Z ff618f76f13f938e13046abb7fac9de3
  # Remove this line to create a well-formed Fossil manifest.

diff --cc manifest.uuid
index f7d89da18276dbabfaebc53199816c38e46c7fcd,fffbbc32ca854d1ee49b5b0bec753a3be75cd6d2..37492bc7db60d366146a0f7f0e0e44eb3fa63cc5
--- 1/manifest.uuid
--- 2/manifest.uuid
+++ b/manifest.uuid
@@@ -1,1 -1,1 +1,1 @@@
- 6d9c29123b6b143b0f7c8f5d018f170c72edfc5b1a4d67edd45e5552def2af6c
 -3f16985dcc47a366b54164c5024f920a79dddd76faeac5e36b4770732ed72c0a
++78c12b4f6ae869c3ea5e368c97b45991442bdd2d3a60935f1e6fc02a8e01cd41