docs: documentation overhaul - archive, user guides, env parity (#62)

* docs: archive CLI runner scripts and Windows Docker guide, update web runner scripts

* docs: overhaul README and DOCKER.md, add 10 user guides

- README: Budget Mode section, corrected Further Reading links, theme badge descriptions, diagnostics expansion
- DOCKER.md: Windows path note, Budget Mode + Include/Exclude sections, env table additions
- docs/user_guides/: 10 new feature guides covering budget mode, include/exclude, locks/replace/permalinks, batch build, theme browser, random build, owned cards, partner mechanics, bracket compliance, quick build & skip controls

* fix: map PriceTimeoutError→503, add budget exceptions to status map; update error_handling.md

* docs: env var parity — add missing vars to .env.example and README table

docs/user_guides/include_exclude.md

@@ -0,0 +1,89 @@
+# Include / Exclude Lists
+
+Pin specific cards into every build or permanently block them from selection.
+
+---
+
+## Overview
+
+The Include / Exclude feature (also called "Must-Haves") lets you control card selection at the individual card level, outside the normal theme and pool logic.
+
+- **Must Include**: cards are always added to the deck, before pool selection runs.
+- **Must Exclude**: cards are never added, regardless of theme, bracket, or pool filtering.
+
+Requires `ALLOW_MUST_HAVES=1` (default: on).
+
+---
+
+## Enabling the UI Controls
+
+The include/exclude buttons are hidden by default to keep the Step 5 interface clean. To show them:
+
+```
+SHOW_MUST_HAVE_BUTTONS=1
+```
+
+When enabled, each card row in Step 5 gains a Must Include (+) and Must Exclude (−) button. You can also manage lists via the quick-add input at the top of the section.
+
+---
+
+## Adding Cards
+
+### Via Step 5 UI
+1. Enable `SHOW_MUST_HAVE_BUTTONS=1`.
+2. In Step 5, click **+** on a card to add it to Must Include, or **−** to add it to Must Exclude.
+3. Use the quick-add input at the top to add cards by name without scrolling.
+
+### Via JSON Config
+Supply lists in your deck config file:
+
+```json
+{
+  "must_include": ["Sol Ring", "Arcane Signet"],
+  "must_exclude": ["Thassa's Oracle"]
+}
+```
+
+Both keys accept an array of card names. Names are matched case-insensitively.
+
+---
+
+## Priority Order
+
+When include/exclude interacts with other filters, this order applies:
+
+1. **Must Exclude** — always wins; card is never selected.
+2. **Must Include** — card is always added, before pool selection.
+3. **Budget filter** — applied to the remaining pool after Must Include cards are inserted.
+4. **Bracket filter** — applied after budget.
+
+Must Include cards are inserted directly and are not subject to budget pool filtering. They may appear as over-budget in the summary if they exceed the ceiling, and they may trigger bracket warnings if they violate bracket rules.
+
+---
+
+## Multi-Copy Archetypes
+
+If a card is in Must Include and the builder detects it supports multi-copy (e.g., Relentless Rats), a count picker dialog appears. Set the desired copy count before confirming.
+
+---
+
+## Conflict Resolution
+
+| Scenario | Behavior |
+|----------|----------|
+| Card is in both Must Include and Must Exclude | A conflict dialog prompts you to resolve before building. Exclude wins if unresolved. |
+| Must Include card not in color identity | Build silently skips the card (does not hard-fail). Verify color identity before including. |
+| Must Include card violates bracket rule | Card is added; bracket compliance report flags it. Resolve in Step 5 or adjust bracket. |
+
+---
+
+## Headless / CLI
+
+Set include and exclude lists in the JSON config. Environment variable overrides are not supported for per-card lists; use the config file.
+
+```json
+{
+  "must_include": ["Swiftfoot Boots"],
+  "must_exclude": ["Demonic Tutor"]
+}
+```