Upgrade Pyright from basic to strict mode

[nitrobass24]

Summary

After completing #249 (Pyright basic mode with 0 errors), upgrade to strict mode for comprehensive type safety enforcement.

Context

#249 adopts Pyright in basic mode which catches:

• None safety (reportOptionalMemberAccess)
• Argument type mismatches (reportArgumentType)
• Attribute access on wrong types (reportAttributeAccessIssue)
• Invalid calls (reportCallIssue)

Strict mode additionally enforces:

• All function parameters must have type annotations
• All return types must be declared
• No implicit Any types
• No unknown member accesses
• Stricter generic type checking

Prerequisites

• Full type safety with Pyright enforcement #249 complete — 0 errors in basic mode, CI enforcing

Implementation

1. Switch pyrightconfig.json from "typeCheckingMode": "basic" to "strict"
2. Audit new errors — likely hundreds of missing annotations, especially in:
   • Test files (most functions unannotated)
   • Callback parameters
   • Dynamic patterns in config.py
3. Fix incrementally or use # type: ignore where annotation burden outweighs value
4. Consider per-directory strict vs basic via pyrightconfig.json executionEnvironments

Acceptance criteria

• pyrightconfig.json set to strict mode
• 0 Pyright errors
• CI enforcing strict mode