XSLT try/catch + typed constructors; TypeTable plumbing; testrunner params; XPath fixes

[michaelgiraldo]

Summary

This is a larger XSLT/XPath enablement pass: try/catch and typed constructors,
runtime TypeTable plumbing, XPath pattern fixes, and improved XSLT test running.
It also adds targeted regressions and refreshes snapshots/docs.

---

Context

This PR advances several XSLT features in one go. The core behavioral additions
are try/catch and typed constructors, which require IR/compiler updates and
TypeTable propagation in the interpreter. I kept runtime changes narrow and
relied on tests for safety. Alongside that, a couple XPath fixes and testrunner
improvements unblock more of the conformance suite.

What changed

XPath parsing / priority

• Fix pattern parsing (nested predicates) and update snapshots.
• Fix union default priority handling.

TypeTable (runtime typing)

• Add core TypeTable infrastructure.
• Thread TypeTable through matching so type annotations are preserved.

XSLT AST → IR → compiler → interpreter

• Parse xsl:try/xsl:catch in AST and update snapshots.
• Extend IR for typing + try/catch.
• Lower new features in the compiler (emit XmlSetType where types are declared).
• Execute templates and try/catch in the interpreter, including rollback.

Typed constructors

• Type propagation for:
  • xsl:element
  • xsl:attribute
  • xsl:copy
  • xsl:copy-of
  • xsl:document

Test runner

• Support XSLT params and dependency gating.

Tests / docs

• Add rollback + type propagation regression tests.
• Refresh snapshots and update conformance/docs.

Commit coverage (explicit)

• xpath: fix pattern parsing and update snapshots
• interpreter: add TypeTable core infra
• interpreter: thread TypeTable through matching
• xslt-ast: parse try/catch and refresh snapshots
• ir: extend XSLT IR model
• compiler: lower XSLT/XPath features
• interpreter: execute templates and try/catch
• testrunner: support xslt params and deps
• xslt-compiler: fix default priority for unions
• Add XSLT regression tests and refresh docs

Review focus (risk boundaries)

• Interpreter changes are limited to TypeTable propagation + try/catch rollback.
• IR changes are additive; existing bytecode paths remain intact.
• XPath changes are scoped to pattern parsing + union priority.

Regression tests added

• test_try_catch_rollback_output (rollback behavior)
• test_type_table_for_typed_constructors (type propagation)

Testing

• cargo test
• cargo run --release --bin xee-testrunner -- check vendor/xpath-tests/
• cargo run --release --bin xee-testrunner -- check vendor/xslt-tests/
• cargo run --release --bin xee-testrunner -- all vendor/xslt-tests/tests/insn/assert/_assert-test-set.xml

Conformance (check runs are filtered):

• XPath QT3: Supported 21859 / Passed 20221 / Failed 0 / Error 0 / Filtered 1638 / Unsupported 9953
• XSLT check: Supported 14595 / Passed 1136 / Failed 0 / Error 0 / Filtered 13459 / Unsupported 0
• XSLT assert set (all): 10/10 passed

Snapshot note

Snapshots updated to reflect the new type_ field on literal elements and fn:
resolution behavior.

[faassen]

Hey, sorry for taking a while to review. I need to improve the way this project is being maintained! I merged another branch this leads to a conflict, could you look into this?

[faassen]

I'm also curious about the interactions with #126