chore: pin lance dependency to v6.0.0 for the v0.28 release branch

Re-targets the v0.28 release branch at lance 6.0.0 stable. Because
lance 6.0.0 directly uses object_store 0.12 while main has moved to
object_store 0.13, the change also reverts the object_store 0.13 port
from #3348:

* workspace `object_store` pin back to 0.12
* `rust/lancedb` aws feature no longer enables `object_store/aws`
* `MirroringObjectStore` and `IoTrackingStore` restored to the 0.12
  trait shape (overrides for `copy`, `delete`, `head`, etc. — no
  `copy_opts`/`rename_opts`/new `delete_stream` signature)
* `listing.rs`: `Path::clone().join(...)` → `Path::child(...)`
* `python/pyproject.toml`: `pylance>=6.0.0` (stable)
* `java/pom.xml`: `lance-core` 6.0.0

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/java.yml

@@ -16,6 +16,7 @@ on:
   push:
     branches:
       - main
+      - release/**
     paths:
       - java/**
       - .github/workflows/java.yml

.github/workflows/license-header-check.yml

@@ -3,6 +3,7 @@ on:
   push:
     branches:
       - main
+      - release/**
   pull_request:
     paths:
       - rust/**

.github/workflows/nodejs.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - release/**
   pull_request:
     paths:
       - Cargo.toml

.github/workflows/python.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - release/**
   pull_request:
     paths:
       - Cargo.toml

.github/workflows/rust.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - release/**
   pull_request:
     paths:
       - Cargo.toml