fix(resources): make TipTracker.get_tip use pending state

[VivienP]

Summary

• Align TipTracker.get_tip() with has_tip so both expose the pending transactional state.
• Fix the contradictory tracker views described in Tip state tracking allows for contradictory states #309.
• Preserve STAR and Vantage pickup behavior with tip tracking enabled: LiquidHandler stages removal from the TipSpot before calling the backend, so Hamilton backends now use the Tip already captured in the pickup operation instead of rereading the mutated TipSpot.
• Update Hamilton tip-type resolution accordingly.
• Add regression coverage for pending add/remove, commit/rollback, and STAR/Vantage pickup with tip tracking enabled.

Hardware uncertainty / UNKNOWN physical state remains out of scope. This PR is independent of #1207.

Test plan

• TipTracker transactional-state tests
• STAR pickup with tip tracking enabled
• Vantage pickup with tip tracking enabled
• Relevant LiquidHandler/Hamilton tests
• Ruff check / format

Combined validation with #1207 on current upstream/main:

• 236 tests passed
• 101 subtests passed
• ruff check pylabrobot passed
• ruff format --check pylabrobot passed

Out of scope

Vantage.pick_up_tips96 with tip tracking enabled is already broken on upstream/main: it checks pending has_tip after the frontend stages removal and fails before get_tip() is involved. This PR does not change that pre-existing behavior.