Unify note path resolution across CLI commands, et. al

[polymorcodeus]

Summary

Adds unified note resolution: park reclassify now accepts a bare basename or a literal path the way park show always did, and closes the findings from a full codebase review (a tilde-expansion gap in --from-file, duplicated error construction, dead exports, and keybinding drift risk).

What's new

• Unified note resolution - park reclassify accepts a bare basename (searched across every configured category folder, archive included) or a literal path (absolute, or relative to the working directory), matching park show.
• No double-join - store.ResolvePath treats any value containing a path separator as a literal path and never joins it onto a category folder.
• Tilde expansion for ingestion - park new --from-file expands ~/$HOME exactly once, in note.IngestFile, so parsing, form preview, and source removal all see the same path; quoted ~/note.md paths previously failed at parse time.
• Single category-error constructor - Config.UnknownCategoryError owns the "unknown category" message for all CLI Before hooks and domain packages (8 hand-written copies removed).
• Keybinding single source - assist reclassify keys are matched in Update from the same key.Binding values that render help (categoryBinding pairs each category name with its binding).

Usage

Command	Purpose
park reclassify <file> -c <category>	<file> accepts a bare basename or a literal path
park new -f <path>	<path> may use ~/$HOME

Behavior changes / guardrails

• Same-category reclassify is still rejected with the same error, whether the note is named by basename, absolute path, or relative path.
• Path-like arguments that do not exist as literal paths return os.ErrNotExist; bare basenames still search every category folder.
• The new --category flag error now uses the shared unknown-category message.
• Dead exported helpers removed: note.Note.HasCompleteMetadata, config.DefaultConfigPath, config.CategoryByKey. All config.Config methods now use pointer receivers; TUI constants renamed to maxWidth/defaultHeight.

Testing

• New tests cover quoted-tilde ingestion, literal-path and relative-path reclassify, no-double-join resolution, the relative-path same-category guard, the shared error constructor, and CLI-level path reclassify.
• Smoke-tested a built binary: basename, absolute, relative, and quoted-tilde invocations all behave as documented.
• make check runs fmt, vet, lint, and tests; all green.