feat: adds acceptSelector and modified selectors

[algebraic-dev]

This PR adds more selectors for TCP and Signals.

It also fixes a problem with Selectors that they cannot be closures over a promise, otherwise it causes the waiter promise to never be dropped.

[leanprover-community-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 5ef7b45afaedd794fb39b0fbd70924b573694a00 --onto 0b2193c7715a55246d0596a4db548c1b5b81562a. You can force Mathlib CI using the force-mathlib-ci label. (2025-10-04 01:13:22)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase aa86d95c0897a5aca9535dad6ffb1fd0f20cd5f1 --onto c32a57e5806476ed6bac4c9cf1bb11cea2b02ea2. You can force Mathlib CI using the force-mathlib-ci label. (2025-10-09 13:51:00)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase aa86d95c0897a5aca9535dad6ffb1fd0f20cd5f1 --onto 14ff08db6f651775ead432d367b6b083878bb0f9. You can force Mathlib CI using the force-mathlib-ci label. (2025-10-17 00:18:33)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase aa86d95c0897a5aca9535dad6ffb1fd0f20cd5f1 --onto 4ce7ad19cea348506876685a19a7e0cca442c6d0. You can force Mathlib CI using the force-mathlib-ci label. (2025-10-17 14:50:40)

[leanprover-bot]

Reference manual CI status:

• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase 5ef7b45afaedd794fb39b0fbd70924b573694a00 --onto d3dda9f6d4428a906c096067ecb75e432afc4615. You can force reference manual CI using the force-manual-ci label. (2025-10-04 01:13:23)
• ❗ Reference manual CI will not be attempted unless your PR branches off the nightly-with-manual branch. Try git rebase aa86d95c0897a5aca9535dad6ffb1fd0f20cd5f1 --onto d3dda9f6d4428a906c096067ecb75e432afc4615. You can force reference manual CI using the force-manual-ci label. (2025-10-09 13:51:04)

[TwoFX]

It would be great to have some theses for these changes.

[TwoFX]

Looks good after addressing the last comment.