M1.10: document patterned and implied CD state transfer

Author: pgousdal

docs/M1_10_PATTERNED_IMPLIED_CD.md

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+# M1.10 Patterned and Implied `CD` State Transfer
+
+M1.10 closes most of the remaining interactive current-directory state gap without introducing an AmShell pattern parser.
+
+## Explicit patterned `CD`
+
+The original Shell supports patterns in `CD`, for example:
+
+```text
+CD SYS:Li#?
+```
+
+AmShell now resolves explicit `CD` patterns with the native V36+ dos.library directory-scanning API:
+
+- `MatchFirst()`
+- `MatchNext()`
+- `MatchEnd()`
+
+The matcher is allowed to interpret AmigaDOS pattern syntax. AmShell does not reimplement `#?`, `?`, alternation, negation, classes, or related semantics.
+
+Only directory matches count. Exactly one matching directory is required before AmShell updates its own process current directory with `CurrentDir()`. If matching fails, is ambiguous, is interrupted, or otherwise does not produce exactly one directory, the original `CD` command line is delegated unchanged to the native system Shell so diagnostics and RC remain native.
+
+This follows the documented Shell behavior that patterned `CD` succeeds for one matching directory and reports an error when more than one directory matches.
+
+## Exact `CD`
+
+Exact paths continue to use `Lock()` and `CurrentDir()`. M1.10 additionally verifies with `Examine()` that the lock is a directory before installing it as the process current directory. Invalid or non-directory targets are delegated to the native Shell for diagnostics and RC.
+
+Quoted exact paths remain supported by the conservative outer decoder introduced in M1.8.
+
+## Path-like implied `CD`
+
+The Shell also supports implied `CD`, where the user omits the `CD` command. M1.10 transfers state directly for path-like standalone tokens containing `:` or `/`, including forms such as:
+
+```text
+SYS:Tools
+/
+//
+:
+```
+
+The target must resolve through `Lock()` to a directory. Pattern syntax is not accepted for implied `CD`, matching the documented Shell restriction that patterns require explicit `CD`.
+
+## Deferred bare-name implied `CD`
+
+A standalone bare directory name such as:
+
+```text
+Tools
+```
+
+can also be an implied `CD` in the original Shell. AmShell deliberately continues to delegate this form for now because command lookup and directory-name precedence must be qualified before intercepting it safely. A directory and an executable may legally share a candidate command name, and compatibility takes priority over convenience.
+
+The combined M1 final qualification must therefore include explicit patterned `CD`, path-like implied `CD`, and command-vs-directory precedence cases before the remaining bare-name implied surface can be declared equivalent.
+
+## Runtime status
+
+Implementation and host/CI structural checks do not constitute runtime qualification. M1.10 runtime execution remains deferred to the combined visible FS-UAE / AmigaOS 2.04 M1 final qualification.