[doc] Update supported Xcode to 26.0 (#23494)

Author: tyler-yankee

doc/_pages/from_source.md

@@ -37,7 +37,7 @@ officially supports when building from source:
 |------------------------------------|--------------|------------|-------|-------|------------------------------|------------|
 | Ubuntu 22.04 LTS (Jammy Jellyfish) | x86_64       | 3.10       | 8.4   | 3.22  | GCC 11 (default) or Clang 15 | OpenJDK 11 |
 | Ubuntu 24.04 LTS (Noble Numbat)    | x86_64       | 3.12       | 8.4   | 3.28  | GCC 13 (default) or Clang 19 | OpenJDK 21 |
-| macOS Sequoia (15)                 | arm64        | 3.13       | 8.4   | 4.1   | Apple LLVM 17 (Xcode 16.4)   | OpenJDK 23 |
+| macOS Sequoia (15)                 | arm64        | 3.13       | 8.4   | 4.1   | Apple LLVM 17 (Xcode 26.0)   | OpenJDK 23 |
 | macOS Tahoe (26) ⁽⁴⁾               | arm64        | TBD        | TBD   | TBD   | TBD                          | TBD        |
 
 "Official support" means that we have Continuous Integration test coverage to

doc/_pages/installation.md

@@ -24,7 +24,7 @@ officially supports:
 | Ubuntu 22.04 LTS (Jammy Jellyfish) | x86_64       | 3.10 ⁽³⁾   | March 2026      |
 | Ubuntu 24.04 LTS (Noble Numbat)    | x86_64       | 3.12 ⁽³⁾   | March 2028      |
 | macOS Sequoia (15)                 | arm64        | 3.13 ⁽³⁾   | October 2026    |
-| macOS Tahoe (26)                   | arm64        | TBD        | October 2027    |
+| macOS Tahoe (26) ⁽⁵⁾               | arm64        | TBD        | October 2027    |
 
 "Official support" means that we have Continuous Integration test coverage to
 notice regressions, so if it doesn't work for you then please file a bug report.
@@ -64,7 +64,7 @@ Drake's pre-compiled binaries:
 |------------------------------------|----------------------------|-------|
 | Ubuntu 22.04 LTS (Jammy Jellyfish) | GCC 11                     | C++20 |
 | Ubuntu 24.04 LTS (Noble Numbat)    | GCC 13                     | C++23 |
-| macOS Sequoia (15)                 | Apple LLVM 17 (Xcode 16.4) | C++23 |
+| macOS Sequoia (15)                 | Apple LLVM 17 (Xcode 26.0) | C++23 |
 | macOS Tahoe (26)                   | TBD                        | TBD   |
 
 Any other configuration not listed here will lead to undefined behavior