2026-08-19 - Crunch continued: worker mode and image placement

170 tests, gate green. D057 and D058 added; 22 crates.

Worker mode done (D057). orbistoun-worker holds both halves; the binary re-invokes itself with a hidden --worker flag. orbistoun-cli run drives a real child process.

Image placement done (D058). A container's span is reserved and every loadable segment copied in, with .bss zeroed. The 96 MB commercial executable now loads: 70.5 MB copied, 32.7 MB zeroed, at 0x400000000000, inside a worker process.

Surprises.

• Host allocation granularity is not the guest page size. D054 found Windows reserves at 64 KiB; placement found the sharper edge - a reservation base must be granularity-aligned too. A span rounded to 4 KiB gets silently rounded down by VirtualAlloc, which this code then correctly refuses as relocation. The two values coincide on Unix, so code written and tested only there would never notice. Now queried via allocation_granularity() rather than assumed.
• Surveying imports must not gate placement. A container with no dynamic table is legitimate - a static binary imports nothing - and refusing to load one conflated "cannot read this file" with "this file needs nothing". Parsing is the gate; surveying is not.
• A missing file is Failed, not Terminated. Two tests asserted the old, worse behaviour and had to be corrected: Failed means the request was wrong, Terminated means a guest was loaded and then stopped. Collapsing them makes "the path was a typo" and "the emulator cannot go further" indistinguishable to anything reading the stream.
• Two of my own test expectations were wrong again, both times because the code had become more correct than the test. Worth noticing as a pattern: when a test fails after a behaviour change, check which one is right before fixing the code.

Next. Relocation, TLS, and the entry jump - the remaining three pieces of phase 4. Every prerequisite now exists and is verified: placement works, the call convention is proven (D056), and the worker gives them a process to happen in.