Add no-nested-try-catch lint rule

[danielchen0]

Summary

• Adds no-nested-try-catch rule that flags try-catch blocks nested inside other try/catch/finally blocks
• Suggests extracting inner try-catch to separate functions

Test plan

• All existing tests pass
• 7 new tests pass
• TypeScript compiles
• Prettier passes

[arnavsurve]

Clean, well-structured addition. The rule implementation follows established patterns (matches no-type-assertion.ts style), tests are thorough (7 cases covering try/catch/finally nesting, deep nesting, sibling try-catch, and the function boundary edge case), and the README documentation is properly updated.

One minor observation: the ancestor walk doesn't stop at function boundaries, so try { const fn = () => { try { ... } catch {} }; } catch {} will be flagged. The test explicitly documents this as intentional/acceptable, which I agree with -- it nudges users toward extracting the inner function outside the try block entirely, which is the cleaner pattern.

The comment on line 12 says "Check if any ancestor is also a TryStatement's block" but the code checks for TryStatement ancestors generally (not just the block property). The logic is still correct since any try nested anywhere within a TryStatement node (block, handler, or finalizer) should be flagged. The comment could be slightly more precise, but this is a pure nit.

LGTM.

🤖 Generated with Claude Code

[arnavsurve]

Nit: The comment says "Check if any ancestor is also a TryStatement's block" but the code checks for any TryStatement ancestor generally (not specifically the .block child). The logic is correct regardless -- just a minor wording thing. Could be simplified to "Check if any ancestor is a TryStatement" to match what the code actually does.